Tire Pressure indicator - how the heck does that work?

Hey guys, proud owner of a '17 Impreza 2.0i MT who just rolled over a nail the other day. I'm on my donut of shame at the moment, but seeing that black wheel on my magnetite gray wagon has me thinking about getting a set of new black shoes.

I'm curious about the tire pressure indicator and how it works though - aside from getting the right size wheel, are there any other considerations I need to check off to make sure the light stays off? Can someone ELI5?

Thanks, guys!