The parking lot is where you can see lots of car being parked. You would need to park your car or you will not have any parking space to park it on. Usually the parking space here gets taken quickly and that is why you need to master the art of parking.
Parking is a skill that you need to master if you want to buy your own car. And in this game, you would have a lot of chance to master that skill without getting in trouble. Maneuver your car into the parking space. You would need to park your car as fast as you can. The game gets harder as you make some progress.