Okay, kiddo, let me explain it to you. So you know how when we play games with our friends, we can choose to join or leave the game anytime we want? Well, that's kind of what's happening with the European Union and the UK.
The European Union is like a big club, where lots of countries in Europe have decided to work together and help each other out. The UK was part of this club too, but a little while ago, they decided they didn't want to be in the club anymore. They wanted to leave and do their own thing.
Now, leaving the club isn't as easy as just saying "I'm out!" There are a lot of things that need to happen before the UK can officially leave the European Union. It's kind of like when we tidy up our toys before we leave our friend's house.
There are a lot of agreements and rules that need to be sorted out before the UK can officially leave. Some of these things include how much money the UK owes the European Union, what will happen to people who live in the UK but are from other countries in the European Union, and how trade and businesses will work between the UK and the other countries in Europe.
So, the UK and the European Union have been working on all these things for a while now, and they're still figuring out the best way to do it. It's like a puzzle, and it takes time to put all the pieces in the right place.
Overall, it's a big change that will affect a lot of people and things, but the grown-ups are working hard to make sure everything gets sorted out in the best way possible.