Label(frame, text='Turn LED ON').grid(row=0, column=0)
Label(frame, text='Turn LED OFF').grid(row=1, column=0)
self.button = Button(frame, text='LED 0 ON', command=self.convert0)
self.button.grid(row=2, columnspan=2)

def convert0(self, tog=[0]):
    tog[0] = not tog[0]
if tog[0]:
    self.button.config(text='LED 0 OFF')
else:
    self.button.config(text='LED 0 ON')
root = Tk()
root.wm_title('LED on & off program')
app = App(root)
root.mainloop()
Beginner - GUI toggle button