from tkinter import *
import calendar
import datetime
now = datetime.datetime.now()
root = Tk()
root.title("time")
root.geometry("400x250")
root.resizable(width=False, height=False)
delay = 1000
def lbl_func():
now = datetime.datetime.now()
label.config(text=now)
label.after(delay, lbl_func)
label = Label(text=now, font="12", pady="10")
label.pack()
lbl_func()
root.mainloop()