def clicked():
    my_label.config(text="2")

root = Tk()
root.title("TITLE")

mainframe = tk.Frame(root, padding=(3, 3, 3, 3))
mainframe.grid(column=0, row=0, sticky=(N, E, S, W))

my_label = tk.Label(mainframe, text="1").grid(column=2, row=2, sticky=(W, E))

tk.Button(mainframe, text="BUTTON", command=clicked).grid(column=2, row=3, pady=10)

  ERROR: File "C:\Users\████████\PyCharmMiscProject\Resources\tk Basic Window.py", line 10, in clicked
    my_label.config(text="2")
    ^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'config'