An assault course is like a giant obstacle course that people go through for fun or to train for something. It's basically like a big playground, but with lots of challenging things to do like climb over walls, crawl under things, and balance on beams.
It's set up like a big maze and you have to figure out how to get through it all while doing all kinds of fun and exciting things along the way. You might have to jump over things, swing on ropes, or climb up tall structures.
It's kind of like a big puzzle that you have to solve with your body, and it's a lot of fun to do with friends or family. Some people even compete in assault course races to see who can get through it the fastest.