app.py

import sys
from PyQt5.QtWidgets import QMainWindow, QApplication, QWidget, QPushButton, QAction, QLineEdit, QMessageBox
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import pyqtSlot

class App(QMainWindow):

    def __init__(self):
        super().__init__()
        self.title = 'Perfect-Pause'
        self.left = 500
        self.top = 100
        self.width = 500
        self.height = 200
        self.initUI()
    
    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)
    
        # Create textbox
        self.textbox = QLineEdit(self)
        self.textbox.move(20, 20)
        self.textbox.resize(280,40)
        
        # Create a button in the window
        self.button = QPushButton('Play', self)
        self.button.move(20,80)
        
        # connect button to function on_click
        self.button.clicked.connect(self.on_click)
        self.show()
    
    @pyqtSlot()
    def on_click(self):
        textboxValue = self.textbox.text()
        #QMessageBox.question(self, 'Message - pythonspot.com', "You typed: " + textboxValue, QMessageBox.Ok, QMessageBox.Ok)
        self.textbox.setText("")

        print(textboxValue)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())