Okay kiddo, let's say you and your friends really love playing soccer and you want to create a club where you can all play together and have fun. Well, this club can be called an "association without lucrative purpose".
This means that the club is something you made just for fun, not to make money or sell things. You and your friends will work together to keep the club going, but no one gets paid for it.
Think of it like a treehouse club where you all meet up and have fun together, but you don't charge anyone money to come in or to have a good time. It's just something fun you created for yourselves.
Even as you grow up and become adults, you can still be part of associations without lucrative purpose, like a group of people who love hiking and organize trips together. It's all about having fun and doing something you enjoy without worrying about making money.