A desiccator is like a little house for things that need to stay super dry. Imagine you have a special toy that can't get wet, so you put it in a little house with a door that keeps all the water out. That's kind of what a desiccator does, only instead of keeping water out, it keeps out moisture in the air that can make things damp or wet.
Inside the desiccator there usually is a little shelf or platform for you to put your thing on. And at the bottom of the desiccator, there's a special material called a desiccant. The desiccant is like a tiny sponge that soaks up any moisture in the air, so it can't get to your toy or whatever you put inside.
When you put your thing inside the desiccator, you have to make sure you close the door tightly. This way the moist air can't get in and your toy stays nice and dry. You can even use a little window on the door to see if everything inside is still nice and dry.
So, a desiccator is just a special container that helps keep things dry and safe from getting wet. It's like a little house with a door that keeps bad things out and a sponge (desiccant) at the bottom that keeps things inside nice and dry.