There is a square in the display and how to get rid of it?

My friend was using my tablet and there was a popup(He doesn't sure what he have seen), and after canceling it, the `Speak Screen` activated and there was a square. The square is still there and if we need to touch somewhere in the screen we need to tap on the icon and after square fit into the icon need to tap two more time to open a app or get the touch into action. My question is how to get rid of this square.

Tab Specs:

1. Model name - iPad Air 2
2. Model number - MGHY2J/A
3. Software version - IOS 15.0.2

Here is a screenshot of the screen. The square fit on the `AssistiveTouch`.