Как сделать фрейм маленького размера, овальным?

Ваше большая недоработка в том что вы не используете менеджеры компоновки и я не вижу всего окна вашего приложения.

Я изменил размеры и цвета стилей некоторых виджетов, чтобы картины мне была понятнее и вам будет нагляднее видно как виджеты расположены в окне у меня.

Из того что я понял, вы вы хотите поменять вид объекта self.frame. Смотрите стили для этого объекта. Обратите внимание на border-radius и другие изменения, которые я отметил в коде.

Изображения, которые я использовал - прикрепляю. Попробуйте сразу с ними, а потом переходите к своим картинкам.

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.Qt import *
# ??? from PyQt5.uic import *


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        self.menuvisible = 0
        MainWindow.setObjectName("MainWindow")
#                               747
        MainWindow.resize(1209, 690)
        MainWindow.setStyleSheet("")
        MainWindow.setAnimated(True)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setStyleSheet("background-color: rgb(34, 31, 46);")
        self.centralwidget.setObjectName("centralwidget")
        
# frame !!!
        self.frame = QtWidgets.QFrame(self.centralwidget)
#        self.frame.setGeometry(QtCore.QRect(0, 160, 161, 591))
        self.frame.setGeometry(QtCore.QRect(0, 185, 161, 495))            # +
# +        
        self.frame.setStyleSheet('''
            .QFrame {
/*          ^ это точка, чтобы стили распространялись только на self.frame */
                background-color: #035397;
                border: 2px solid #FFAA4C;
                border-radius: 25px;                 /* <---- border-radius */
            }
        ''')
        self.frame.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.frame.setFrameShadow(QtWidgets.QFrame.Raised)
        self.frame.setObjectName("frame")
        
        self.weapon = QtWidgets.QPushButton(self.frame)
        self.weapon.setGeometry(QtCore.QRect(40, 100, 121, 41))
        sizePolicy = QtWidgets.QSizePolicy(
            QtWidgets.QSizePolicy.Preferred, QtWidgets.QSizePolicy.Fixed)
        sizePolicy.setHorizontalStretch(0)
        sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(self.weapon.sizePolicy().hasHeightForWidth())
        self.weapon.setSizePolicy(sizePolicy)
        font = QtGui.QFont()
        font.setFamily("Copperplate Gothic Bold")
        font.setPointSize(14)
        font.setBold(False)
        font.setWeight(50)
        self.weapon.setFont(font)
        self.weapon.setStyleSheet("QPushButton {\n"
"    ;\n"
"    color: rgb(78, 75, 94);      \n"
"    background-color: rgba(255, 255, 255, 0);\n"
"    padding: 5px;\n"
"    }\n"
"\n"
"QPushButton:hover {\n"
"   \n"
"    \n"
"    \n"
"    color: rgb(168, 168, 168);\n"
"    }\n"
"\n"
"QPushButton:pressed {\n"
"    border-style: inset;\n"
"   \n"
"    \n"
"    color: rgb(214, 214, 214);\n"
"    }")
        self.weapon.setInputMethodHints(QtCore.Qt.ImhNone)
        self.weapon.setAutoExclusive(False)
        self.weapon.setObjectName("weapon")
        
        self.spravka = QtWidgets.QPushButton(self.frame)
        self.spravka.setGeometry(QtCore.QRect(40, 540, 111, 41))
        sizePolicy = QtWidgets.QSizePolicy(
            QtWidgets.QSizePolicy.Preferred, QtWidgets.QSizePolicy.Fixed)
        sizePolicy.setHorizontalStretch(0)
        sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(self.spravka.sizePolicy().hasHeightForWidth())
        self.spravka.setSizePolicy(sizePolicy)
        font = QtGui.QFont()
        font.setFamily("Copperplate Gothic Bold")
        font.setPointSize(12)
        font.setBold(False)
        font.setWeight(50)
        self.spravka.setFont(font)
        self.spravka.setStyleSheet("QPushButton {\n"
"    ;\n"
"    \n"
"    color: rgb(78, 75, 94);\n"
"    background-color: rgba(255, 255, 255, 0);\n"
"    padding: 5px;\n"
"\n"
"    }\n"
"QPushButton:hover {\n"
"   \n"
"    \n"
"    color: rgb(168, 168, 168);\n"
"    }\n"
"\n"
"QPushButton:pressed {\n"
"    border-style: inset;\n"
"   \n"
"    color: rgb(214, 214, 214);\n"
"    }")
        self.spravka.setInputMethodHints(QtCore.Qt.ImhNone)
        self.spravka.setAutoExclusive(False)
        self.spravka.setObjectName("spravka")
        
        self.label_10 = QtWidgets.QLabel(self.frame)
        self.label_10.setGeometry(QtCore.QRect(-20, 440, 61, 41))
        self.label_10.setText("")
        self.label_10.setPixmap(QtGui.QPixmap("ball.png"))
        self.label_10.setObjectName("label_10")
        
        self.label_9 = QtWidgets.QLabel(self.frame)
        self.label_9.setGeometry(QtCore.QRect(0, 100, 41, 41))
        self.label_9.setText("")
        self.label_9.setPixmap(QtGui.QPixmap("ball.png"))
        self.label_9.setObjectName("label_9")

# menu !!!       
        self.menu = QtWidgets.QPushButton(self.frame)
        self.menu.clicked.connect(self.showmenu) 
        self.menu.setGeometry(QtCore.QRect(10, 20, 51, 51))

        self.menu.setStyleSheet(
# --- "background-image: url(ball.png);\n"
# + vvvvvvvvvvvvvvvvvvvvvv
"border-image: url(Ok.png);"                                           # +++
 
# ??? "border: 1px solid rgba(255, 255, 255, 0);\n"

"background-color: #035397;"                                           # +++
"")
        self.menu.setText("")
        self.menu.setObjectName("menu")
        
        self.frame_2 = QtWidgets.QFrame(self.centralwidget)
        self.frame_2.setGeometry(QtCore.QRect(0, 0, 1211, 21))
        self.frame_2.setStyleSheet("background-color: rgb(46, 243, 63);")
        self.frame_2.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.frame_2.setFrameShadow(QtWidgets.QFrame.Raised)
        self.frame_2.setObjectName("frame_2")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(610, 90, 231, 41))
        font = QtGui.QFont()
        font.setFamily("Copperplate Gothic Bold")
        font.setPointSize(28)
        self.label.setFont(font)
        self.label.setStyleSheet("color: rgb(253, 253, 253);")
        self.label.setAlignment(QtCore.Qt.AlignCenter)
        self.label.setObjectName("label")
        self.line = QtWidgets.QFrame(self.centralwidget)
        self.line.setGeometry(QtCore.QRect(600, 130, 241, 2))
        self.line.setFrameShape(QtWidgets.QFrame.HLine)
        self.line.setFrameShadow(QtWidgets.QFrame.Sunken)
        self.line.setObjectName("line")
        
        self.frame_3 = QtWidgets.QFrame(self.centralwidget)
        self.frame_3.setGeometry(QtCore.QRect(260, 180, 261, 161))
        self.frame_3.setStyleSheet("background-color: rgb(46, 43, 63);\n"
"border: 2px solid #2e2b3f;\n"
"border-radius: 10")
        self.frame_3.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.frame_3.setFrameShadow(QtWidgets.QFrame.Raised)
        self.frame_3.setObjectName("frame_3")
        self.label_3 = QtWidgets.QLabel(self.frame_3)
        self.label_3.setGeometry(QtCore.QRect(70, 0, 121, 41))
        font = QtGui.QFont()
        font.setFamily("Bahnschrift SemiBold")
        font.setPointSize(22)
        font.setBold(True)
        font.setWeight(75)
        self.label_3.setFont(font)
        self.label_3.setStyleSheet("color: rgb(194, 194, 194);")
        self.label_3.setAlignment(QtCore.Qt.AlignCenter)
        self.label_3.setObjectName("label_3")
        self.label_4 = QtWidgets.QLabel(self.frame_3)
        self.label_4.setGeometry(QtCore.QRect(70, 60, 121, 61))
        font = QtGui.QFont()
        font.setFamily("Bahnschrift SemiBold")
        font.setPointSize(22)
        font.setBold(True)
        font.setWeight(75)
        self.label_4.setFont(font)
        self.label_4.setStyleSheet("")
        self.label_4.setAlignment(QtCore.Qt.AlignCenter)
        self.label_4.setObjectName("label_4")
        
        self.textBrowser = QtWidgets.QTextBrowser(self.centralwidget)
        self.textBrowser.setGeometry(QtCore.QRect(570, 170, 256, 351))
        self.textBrowser.setStyleSheet("background-color: rgb(46, 43, 63);\n"
"border: 2px solid #2e2b3f;\n"
"border-radius: 10")
        self.textBrowser.setObjectName("textBrowser")
        
        self.frame_4 = QtWidgets.QFrame(self.centralwidget)
        self.frame_4.setGeometry(QtCore.QRect(560, 720, 201, 20))
        self.frame_4.setStyleSheet("background-color: rgb(46, 43, 63);\n"
"border: 2px solid #2e2b3f;\n"
"border-radius: 10")
        self.frame_4.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.frame_4.setFrameShadow(QtWidgets.QFrame.Raised)
        self.frame_4.setObjectName("frame_4")
        self.label_5 = QtWidgets.QLabel(self.frame_4)
        self.label_5.setGeometry(QtCore.QRect(50, -2, 101, 21))
        font = QtGui.QFont()
        font.setFamily("Bahnschrift SemiBold SemiConden")
        font.setPointSize(12)
        font.setBold(True)
        font.setWeight(75)
        self.label_5.setFont(font)
        self.label_5.setAlignment(QtCore.Qt.AlignCenter)
        self.label_5.setObjectName("label_5")
        
        self.textBrowser_2 = QtWidgets.QTextBrowser(self.centralwidget)
        self.textBrowser_2.setGeometry(QtCore.QRect(260, 360, 261, 161))
        self.textBrowser_2.setStyleSheet("background-color: rgb(46, 43, 63);\n"
"border: 2px solid #2e2b3f;\n"
"border-radius: 10")
        self.textBrowser_2.setObjectName("textBrowser_2")
        
        self.line_2 = QtWidgets.QFrame(self.centralwidget)
        self.line_2.setGeometry(QtCore.QRect(309, 391, 161, 2))
        self.line_2.setFrameShape(QtWidgets.QFrame.HLine)
        self.line_2.setFrameShadow(QtWidgets.QFrame.Sunken)
        self.line_2.setObjectName("line_2")
        
        self.line_3 = QtWidgets.QFrame(self.centralwidget)
        self.line_3.setGeometry(QtCore.QRect(331, 219, 121, 2))
        self.line_3.setFrameShape(QtWidgets.QFrame.HLine)
        self.line_3.setFrameShadow(QtWidgets.QFrame.Sunken)
        self.line_3.setObjectName("line_3")
        
        self.textBrowser_3 = QtWidgets.QTextBrowser(self.centralwidget)
        self.textBrowser_3.setGeometry(QtCore.QRect(870, 170, 256, 351))
        self.textBrowser_3.setStyleSheet("background-color: rgb(46, 43, 63);\n"
"border: 2px solid #6c6c00;\n"
"border-radius: 10")
        self.textBrowser_3.setObjectName("textBrowser_3")
        
        self.line_4 = QtWidgets.QFrame(self.centralwidget)
        self.line_4.setGeometry(QtCore.QRect(897, 200, 201, 2))
        self.line_4.setFrameShape(QtWidgets.QFrame.HLine)
        self.line_4.setFrameShadow(QtWidgets.QFrame.Sunken)
        self.line_4.setObjectName("line_4")

# !!!
        self.frame_5 = QtWidgets.QFrame(self.centralwidget)
#        self.frame_5.setGeometry(QtCore.QRect(0, -1, 161, 170)) 
        self.frame_5.setGeometry(QtCore.QRect(0, 22, 161, 161))
        self.frame_5.setStyleSheet(
#            "background-color: rgb(46, 43, 63);"
            "background-color: #FF4C29;"              
        )
        self.frame_5.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.frame_5.setFrameShadow(QtWidgets.QFrame.Raised)
        self.frame_5.setObjectName("frame_5")
        
# !!!        
        self.mainmenu = QtWidgets.QPushButton(self.frame_5)
        self.mainmenu.setGeometry(QtCore.QRect(0, 0, 161, 161))
        
        self.mainmenu.setStyleSheet(
# "background-image: url(:/Fone/Изображения/_Logotip_Proz3.png); \n"

"border-image: url(Ok.png);"                                        # +++
"background-color: rgb(34, 31, 46);"                                # +++

# ??? "border: 3px solid rgba(255, 0, 0, 222);\n"
"")
        self.mainmenu.setText("")
        self.mainmenu.setObjectName("mainmenu")
        self.frame_2.raise_()
        self.frame.raise_()
        self.label.raise_()
        self.line.raise_()
        self.frame_3.raise_()
        self.textBrowser.raise_()
        self.frame_4.raise_()
        self.textBrowser_2.raise_()
        self.line_2.raise_()
        self.line_3.raise_()
        self.textBrowser_3.raise_()
        self.line_4.raise_()
        self.frame_5.raise_()
        MainWindow.setCentralWidget(self.centralwidget)
        self.action = QtWidgets.QAction(MainWindow)
        self.action.setObjectName("action")

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.weapon.setText(_translate("MainWindow", "Weapons"))
        self.spravka.setText(_translate("MainWindow", "Reference"))
        self.label.setText(_translate("MainWindow", "Main Menu"))
        self.label_3.setText(_translate("MainWindow", "Версия"))
        self.label_4.setText(_translate("MainWindow", "1.0 BETA"))
        self.textBrowser.setHtml(_translate("MainWindow", "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"http://www.w3.org/TR/REC-html40/strict.dtd\">\n"
"<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\n"
"p, li { white-space: pre-wrap; }\n"
"</style></head><body style=\" font-family:\'MS Shell Dlg 2\'; font-size:8.25pt; font-weight:400; font-style:normal;\">\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:12pt; font-weight:600; color:#c2c2c2;\">ApexHelper</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:12pt; font-weight:600;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:12pt;\">Эта программа предназначена для того, чтобы помочь новичкам или опытным игрокам более лучше освоить игру</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:12pt;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:12pt; font-weight:600; color:#c2c2c2;\">_Apex Legends_</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:12pt; font-weight:600; color:#c2c2c2;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:12pt;\">Тут ты найдёшь подробное описание каждого оружия,</span><span style=\" font-size:12pt; text-decoration: underline;\"> </span><span style=\" font-size:12pt;\">обвеса и прочих вещей.</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:12pt;\"><br /></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:12pt;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:12pt; font-style:italic; color:#c2c2c2;\">С уважением, Разработчик </span><span style=\" font-size:12pt; font-weight:600; font-style:italic; color:#c2c2c2;\">ApexHelper</span><span style=\" font-size:12pt; color:#c2c2c2;\">.</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:12pt;\"><br /></p></body></html>"))
        self.label_5.setText(_translate("MainWindow", "Всё для вас!"))
        self.textBrowser_2.setHtml(_translate("MainWindow", "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"http://www.w3.org/TR/REC-html40/strict.dtd\">\n"
"<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\n"
"p, li { white-space: pre-wrap; }\n"
"</style></head><body style=\" font-family:\'MS Shell Dlg 2\'; font-size:8.25pt; font-weight:400; font-style:normal;\">\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:16pt; font-weight:600; color:#c2c2c2;\">Информация</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:16pt; font-weight:600;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:12pt;\">Программа находится в разработке, поэтому, пока что присудствует не вся информация </span></p></body></html>"))
        self.textBrowser_3.setHtml(_translate("MainWindow", "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"http://www.w3.org/TR/REC-html40/strict.dtd\">\n"
"<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\n"
"p, li { white-space: pre-wrap; }\n"
"</style></head><body style=\" font-family:\'MS Shell Dlg 2\'; font-size:8.25pt; font-weight:400; font-style:normal;\">\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:16pt; color:#c2c2c2;\">Кому принадлежит</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:16pt;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:16pt;\">Все данные, изображения и прочее из программы, принадлежат компании</span></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:16pt;\"> </span></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:14pt; font-weight:600; color:#6f6f0a;\">Respawn Entertainment</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:14pt; font-weight:600;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:14pt;\">Никому более.</span></p>\n"
"<p align=\"center\" style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; font-size:14pt;\"><br /></p>\n"
"<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><span style=\" font-size:14pt;\">Их материал был повзаимствован для помощи игрокам.</span></p></body></html>"))
        self.action.setText(_translate("MainWindow", "справка"))

    def showmenu(self):
        self.anim = QPropertyAnimation(self.frame, b'size')
        self.anim.setDuration(250)
        if self.menuvisible==0:
# !!!                                         751 -> self.frame.height()        
            self.anim.setStartValue(QSize(50, self.frame.height()))    
            self.anim.setEndValue(QSize(161, self.frame.height()))
            self.menuvisible = 1
        else:
            self.anim.setStartValue(QSize(161,self.frame.height()))
            self.anim.setEndValue(QSize(50, self.frame.height()))
            self.menuvisible = 0
            #self.anim.finished.connect(self.hidemenu)
        self.frame.show()
        self.anim.start()

# ??? import ApexFone
# ??? import menu


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

Ok.png

ball.png