MouseButton1Click
is a function. Therefore, you need to integrate it with the correct syntax. You should use it like this:
1 | script.Parent.TextButton.MouseButton 1 Click:connect( function () |
or
5 | script.Parent.TextButton.MouseButton 1 Click:connect(Click) |
So, in your case you're attempting to change the text of the TextButton. To do that, we'll use the function, and have it set up like this:
1 | script.Parent.TextButton.MouseButton 1 Click:connect( function () |
2 | script.Parent.TextButton.Text = "121" |
That's all there is to it! So now, this will fire the function, and then change the text to "121".
Anyways, if you have any further problems/questions, please leave a comment below, and I'll see what I can do. Hope I helped :P
-Dyler3