Hydrogen is like really special magic gas that can be used to make a special kind of vehicle that doesn't need gasoline or diesel to run. Instead of burning fuel to move forward like in a regular car, hydrogen vehicles use something called a fuel cell to make energy.
The fuel cell combines hydrogen and oxygen from the air to create electricity. This electricity then powers an electric motor that makes the car go. The only thing that comes out of the tailpipe is water! It's like magic!
But, getting the hydrogen is a little tricky. It is stored as a compressed gas or a liquid, and it needs to be made at hydrogen stations. You can't just get it from a regular gas station like you do with gasoline.
Also, right now, there aren't many hydrogen stations, so it's not so easy to have a hydrogen vehicle as it is a gas car. But, maybe someday, when there are more stations, we will see many more hydrogen vehicles on the road.