NameError issue with daughter's newb code

[BashBedlam]

Your problem is coming from line 15. You probably want a button instead of a text widget since you're trying to give it a command to execute. That being said, in tkinter you can't assign a function to a command that requires arguments so you may want to make the variable index a global. Also, you can't include parentheses when assigning a function to a command. Here is the working code but you may want to separate the button and the first text widget.

from tkinter import *
 
root = Tk()
root.geometry("200x400")
root.title("Rainbow")
 
codes = ['#FF0000', '#FFA500', '#FFFF00', '#008800', '#0000FF', '#000080', '#4B0082']
colours = ["red", "orange", "yellow", "green", "light blue", "blue", "violet"]
index = 0

def chang_text():
    colour_name.config(text=colours[index])
    colour_code.config(text=codes[index])
 
colour_name = Button(font='Arial, 14', bg='#ffffff', width=20, height=2, command=chang_text)
colour_name.pack(padx=5)
colour_code = Label(font='Arial, 14', bg='#ffffff', width=20, height=2)
colour_code.pack(padx=5)
 
root.mainloop()