How can I get rid of numbers popping up on my iPhone screen?

I'm going to guess you have Voice Control with Overlay turned on. To turn it off:

 Settings > Accessibility > Voice Control and turn off the "Overlay" option or disable Voice Control entirely.

Can you please provide more detail? What are you doing when the numbers pop up on your screen? What app are you using? If you could provide a screenshot, it would help us understand what's going on.

What’a numbers pop up I don’t understand please