from tkinter import Tk, Label, Entry, Button


root = Tk()
root.wm_geometry("600x400")
root.resizable = False
root.config(background="green")


def change_label_text() -> None:
    global label
    label.config(text=entry.get())


entry = Entry(root)
label = Label(root, text="Ви нічого не ввели")
button = Button(
    root, text="Ок", font="Сalibri 13",
    command=change_label_text
)


label.pack()
entry.pack()
button.pack()
root.mainloop()