If you are 5 years old, the way I would explain it is that Bitcoin is like lego pieces, they're fun and easy to play with, you could part with them or trade them in pieces or as a set, could be frustrated at times, they could be cheap or expensive depending on brands or if they're counterfeit, and some could be worth a fortune, for example some of Harry Potter's legos are in the thousands of dollars now even though they were less than $100 a few years ago.