Okay kiddo, imagine your computer is like a super important fortress, and you want to make sure that all your treasures inside are safe from bad guys. That's where computer security comes in!
A computer security model is like a whole bunch of different locks and guards that surround your fortress, to keep out any sneaky thieves who might try to break in.
There are a few different ways that people can try to break in to your fortress, so there are different kinds of locks and guards you can use to keep them out. One way they might try to get in is by tricking your computer into thinking they are someone who is allowed to come in. To stop this, you can put a lock on the door that only lets in people with the right password or fingerprint.
Another way bad guys might try to get into your fortress is by climbing over the walls. To stop them, you can hire a team of guards to walk around the perimeter and make sure nobody gets over the walls.
There are also different kinds of locks and guards to protect different parts of your fortress. For example, you might want to put a lock on your treasure chest, so even if someone does get in, they can't get your valuable coins and gems.
All of these locks and guards make up a computer security model, which is like a blueprint for how to keep your fortress safe. Different people use different models depending on how valuable their treasures are and how sneaky the bad guys are. But just like a real fortress, the more locks and guards you have, the harder it is for anyone to sneak in and steal your stuff!