Hey there little buddy! So, you know how there are countries like the United States, Canada, and Mexico? Well, imagine if they all decided to become one big country and work together to make decisions for everyone. That's kind of like a federal world government.
It would mean that there would be one big group of people that would make rules and laws for everyone in the world, and each country would still have their own leaders and governments but they would all work together to make sure everyone was happy and safe.
It's kind of like having a really big family where all the aunties, uncles, and cousins get together and plan things for everyone. It would be a big change and not everyone thinks it's a good idea, but it's something some people talk about when they want to make the world a better place for everyone.