An air mattress is like a bed that you can fill up with air. It's much lighter and easier to move around than a regular bed, and you can take it wherever you want, even to camp in the mountains!
To fill up the air mattress, you'll need a special air pump that works like a big straw. You plug the pump into the mattress, and then you pump the air in with your hands or a foot pedal.
Once the mattress is full of air, it will be really bouncy and fun to jump on! But if you want to sleep on it, you'll need to let a little bit of air out first. This will make it more comfortable to lay on, just like a regular bed.
When you're done using the air mattress, you can let the air out and fold it up into a tiny package. Then you can store it in a closet or under your bed until you need it again.