Okay kiddo, do you know what "fit" means? It means that something is right for a certain purpose. Like, if you want to play basketball, you need shoes that fit your feet and help you run and jump.
Now, "world fit" is kind of like that. It means that the world, or the whole planet, is set up in a way that works well for everyone and everything on it.
So think about it like this - the world is like a giant puzzle. There are lots of different pieces that all need to fit together perfectly so that everything can work the way it's supposed to. For example, plants need sunlight and water to grow. Animals need plants and other animals to eat.
But sometimes, things don't fit together quite right. People cut down too many trees, for example, so animals lose their homes and can't find food. Or factories make too much pollution, which makes the air and water dirty and hard to breathe.
When things aren't "world fit," it can cause problems for people and animals all over the world. That's why grown-ups are always trying to think of ways to make the world a better place - like using clean energy instead of oil, or recycling things we've used up so we don't waste them.
So, world fit means making sure everything in the world works together smoothly, like pieces of a puzzle. And if we do that, everything will be happier, healthier, and better!