Skip to last block for actual question, everything else is about what i see and dont understand.

Machine learning and artificial intelligence is very interesting to me, ive watched a few videos but i cant manage to wrap my mind around it.

I see a few people starting out with projects that appear to be an easy start, but i of course have no idea, were they make a self-driving car in GTA (crashes alot, but still) or teach the program to complete levels in a game (snake, mario, run forrest)

I watched a few videos on Jabrils youtube channel that seemed to make alot of sense, until one point..

How does the AI know when it hit a wall?
How does it know where the walls are?
How does it measure the distance? How does it know when it has respawned?

I find it really, really confusing.
Can anyone of you geniuses suggest me anything to get into this? Id prefer if the goal was to make an AI using machine learning, that can complete some basic game, like in Jabrils videos.