QLabel have an occurring while in displaying GUI byte or ASCII

On a school assignment, I starting a pyqt project and quite new to this.

I would like to display a label inside a pyqt5 app but facing a ASCII string or bytes error , any ideas ?

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QLabel
from PyQt5.QtCore import pyqtSlot

class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title = 'title'
        self.left = 10
        self.top = 10
        self.width = 640
        self.height = 480
        self.initUI()


    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        self.labl = QLabel(self)
        self.labl.setText('abc')

        button = QPushButton('button', self)        
        button.move(170,300)
        button.clicked.connect(self.on_click)

        self.show()

    @pyqtSlot
    def on_click():
        self.labl = QLabel(self)
        self.labl.setText('abc')


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

This is the error I do see in the Console

builtins.TypeError: bytes or ASCII string expected not 'function'

>Solution :

resolved
fixed this to @pyqtSlot() and def on_click(self):

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QLabel
from PyQt5.QtCore import pyqtSlot

class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title = 'title'
        self.left = 10
        self.top = 10
        self.width = 640
        self.height = 480
        self.initUI()


    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        self.labl = QLabel(self)
        self.labl.setText('abc')

        button = QPushButton('button', self)        
        button.move(170,300)
        button.clicked.connect(self.on_click)

        self.show()

    @pyqtSlot()
    def on_click(self):
        self.labl = QLabel(self)
        self.labl.setText('abc')


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