sheets.py

import gspread
from oauth2client.service_account import ServiceAccountCredentials
from pprint import pprint


def spreadhseet_thingy():
    scope = ["https://spreadsheets.google.com/feeds",'https://www.googleapis.com/auth/spreadsheets',"https://www.googleapis.com/auth/drive.file","https://www.googleapis.com/auth/drive"]
    creds = ServiceAccountCredentials.from_json_keyfile_name("creds.json", scope) #enter the name of your json file also make sure that it is in the same folder as this file
    client = gspread.authorize(creds)
    sheet = client.open("testing").sheet1  # This is the name of your spreadsheet
    data = sheet.get_all_records()
    insertRow = [value, value2, value3]
    sheet.append_row(insertRow)
    pprint(len(data)) #checks how many rows have been filled


##########################################################
#THE CODE BELOW HAS BEEN SEPARATED FOR YOUR UNDERSTANDING#
##########################################################

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(498, 332)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(340, 240, 75, 23))
        self.pushButton.setAutoRepeat(False)
        self.pushButton.setObjectName("pushButton")
        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(170, 20, 271, 21))
        self.lineEdit.setObjectName("lineEdit")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(60, 20, 101, 21))
        font = QtGui.QFont()
        font.setPointSize(12)
        self.label.setFont(font)
        self.label.setObjectName("label")
        self.lineEdit_2 = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_2.setGeometry(QtCore.QRect(170, 90, 271, 21))
        self.lineEdit_2.setObjectName("lineEdit_2")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setGeometry(QtCore.QRect(60, 90, 101, 21))
        font = QtGui.QFont()
        font.setPointSize(12)
        self.label_2.setFont(font)
        self.label_2.setObjectName("label_2")
        self.lineEdit_3 = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_3.setGeometry(QtCore.QRect(170, 160, 271, 21))
        self.lineEdit_3.setObjectName("lineEdit_3")
        self.label_3 = QtWidgets.QLabel(self.centralwidget)
        self.label_3.setGeometry(QtCore.QRect(60, 160, 101, 21))
        font = QtGui.QFont()
        font.setPointSize(12)
        self.label_3.setFont(font)
        self.label_3.setObjectName("label_3")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 498, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

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

        self.pushButton.clicked.connect(self.addItem)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Submit"))
        self.label.setText(_translate("MainWindow", "Enter Name"))
        self.label_2.setText(_translate("MainWindow", "Enter Item"))
        self.label_3.setText(_translate("MainWindow", "Enter Quantity"))

    def addItem(self):
        global value
        value = self.lineEdit.text() # Get the value of the lineEdit
        self.lineEdit.clear() # Clear the text
        global value2
        value2 = self.lineEdit_2.text()
        self.lineEdit_2.clear()
        global value3
        value3 = self.lineEdit_3.text()
        self.lineEdit_3.clear()
        print(value, value2, value3)
        spreadhseet_thingy()


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_())