Okay kiddo, so you know how sometimes you want to play a game with your friends, but you don't have a game board or anything? You just use whatever toys or objects you have around you to make up the game as you go. That's kind of what an ad hoc wireless network is like.
Instead of having a big fancy network set up with lots of wires and machines, you just use whatever devices you have around you to connect to each other and share information. This could be your phone, your tablet, your computer, or even a toy that can connect to Wi-Fi.
It's called "ad hoc" because it's made up on the spot, kind of like when you make up a game with your friends. You don't need any special equipment or planning ahead of time - you just start connecting your devices together and sharing information.
It's really useful if you're in a place where there's no internet or Wi-Fi network available, but you still need to share information or play a game with your friends. You can create your own little network wherever you are, without having to rely on any outside help.
So an ad hoc wireless network is just a fancy way of saying that you and your friends can connect your devices together and share information without needing any special equipment or planning ahead of time. Cool, huh?