Okay kiddo, so you know how sometimes you get some money from your parents to buy things you need or want? Well, the same thing happens with countries, but instead of buying toys or candies, they use their money to make their country stronger and keep their people safe.
One way they do this is by spending money on their military. The United States, for example, spends a lot of money on its military - more than any other country in the world.
They use this money to pay for things like soldiers, weapons, planes, and ships. They also use it to build new military bases and improve the ones they already have. Basically, they want to be prepared for any threats or dangers that might come their way, so they make sure their military is strong and ready to protect the country and its people.
But some people think that the US is spending too much money on its military and that it could be using that money to do other things, like building better schools or helping people who are struggling to make ends meet.
Overall, the military budget is just a fancy way of saying how much money a country is spending on its military to keep its people safe.