qtime = time.time()
qtime = int(qtime)
print(qtime) #выводит время начала работы программы
    def bt_push(self):
        global stime
        stime = 0
        ptime = time.time()
        ptime = int(ptime)
        stime = ptime - stime
        print(stime) #выводит время нажатия кнопки
        print(ptime) #выводит время нажатия кнопки

 stime = ptime - stime

 stime = ptime - 0

 import time
import pandas as pd
from PyQt5 import uic, QtCore, QtGui, QtWidgets, QtTest
from openpyxl import load_workbook, workbook
from openpyxl.styles import Font, Border, Side, Alignment
#Создание переменной с текущим временем от начала эпохи:
qtime = time.time()
qtime = int(qtime)
print(qtime)
class PySide2:
    pass
class Ui_MainWindow(object):
        # Функции нажатий на кнопку:
        def bt_push(self):
        global stime
        stime = 0
        ptime = time.time()
        ptime = int(ptime)
        stime = ptime - stime
        print(stime)
        print(ptime)
#Создание главного окна:
        def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(1200, 800) #1200, 800
        MainWindow.setToolTipDuration(-5)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
 #Кнопки:
        #Перерыв:
        self.bt_pereriv = QtWidgets.QPushButton(self.centralwidget)
        self.bt_pereriv.setGeometry(QtCore.QRect(180, 120, 180, 70))
        font = QtGui.QFont()
        font.setPointSize(12)
        font.setBold(False)
        font.setWeight(50)
        self.bt_pereriv.setFont(font)
        self.bt_pereriv.setAutoFillBackground(False)
        self.bt_pereriv.setCheckable(True)
        self.bt_pereriv.setObjectName("bt_pereriv")
MainWindow.setCentralWidget(self.centralwidget)
    #Нажатие кнопок:
        self.retranslateUi(MainWindow)
        #Перерыв:
        self.bt_pereriv.pressed.connect(self.label_zadacha_name.clear)  # type: ignore
        self.bt_pereriv.pressed.connect(self.bt_push)
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_())

  
qtime =int(qtime)
stime = qtime

 ptime = int(time.time())
stime = ptime - stime
print(stime) 
stime = ptime

 import time
import tkinter
qtime = stime = int(time.time())
def show():
    global stime
    ptime = int(time.time())
    print(ptime-stime)
    stime = ptime
    
root = tkinter.Tk()
but = tkinter.Button(root, text='time', command=show)
but.pack()
root.mainloop()