Alright kiddo, so imagine you have a toy gun that shoots little plastic balls. When you pull the trigger, something inside the gun makes the plastic ball come out of the barrel.
Now, real guns work kind of the same way. But instead of a plastic ball, real guns shoot things like bullets or shot pellets. And there are different ways that the gun makes those things come out of the barrel.
The way a gun works is called its "action". There are several different types of actions, but we'll start with the most common one: the "bolt-action".
Imagine that your toy gun has a little door on the top that you have to open to put the plastic ball inside. When you pull the trigger, something inside the gun moves the plastic ball from the magazine (where all the balls are stored) into the barrel. This is kind of like how a bolt-action gun works.
In a bolt-action gun, there's a little lever (called the "bolt") that you push back and then forward to load a bullet into the barrel. You then pull the trigger like with a toy gun, and the bullet comes out. After you fire the gun, you have to pull the bolt back again to get rid of the empty shell casing, and then push it forward again to load the next bullet.
There are other types of actions, of course. For example, "lever-action" guns work kind of like old-fashioned cowboy guns. Instead of a bolt, you have a little lever under the gun. You push it down and then back up to load a bullet into the barrel, and then pull the trigger to fire. You then repeat the lever motion to load the next bullet.
Some guns have "semi-automatic" actions. This means that after you fire the gun, it automatically loads the next bullet into the barrel for you. All you have to do is keep pulling the trigger until you run out of bullets.
And then there are "automatic" guns, which keep firing as long as you hold down the trigger. These guns are very dangerous and are usually illegal for regular people to own.
So that's how gun actions work, in a nutshell. Different actions make guns work in different ways. But the important thing to remember is that guns should always be treated with respect and used safely.