Okay kiddo, imagine you have a big toy castle that you like to play with. The castle is really tall, so you can't reach the top of it easily.
Now imagine that someone came along and saw that you were having a hard time reaching the top of the castle, so they cut the castle in half.
Now you have two smaller castle pieces instead of one big one. The top half, which is too tall for you to reach, is gone, and you can play with the bottom half much more easily.
That's kind of what a half tower is like. When you use a computer, there's a big part that has all the important stuff inside of it, called the tower. It's usually really big and heavy, and it sits next to your desk or on the floor.
A half tower is like someone took that big tower and cut it in half. They got rid of the top half, which doesn't really do anything except take up space, and they made the bottom half smaller so it's easier to move around and put on your desk.
It's like taking that big toy castle and making it smaller and easier to play with. So if you ever hear someone talking about a half tower computer, you'll know it's just a smaller, more manageable version of the big tower computers you've probably seen before.