Okay kiddo, so have you heard of the word "lithium" before? It's a type of element that we use for batteries, like the one in your toy car. And aluminum is a type of metal we use to make cans for soda pop.
Lithium aluminium hydride is a big name for a special kind of powder. This powder is made up of some lithium, some aluminum, and some hydrogen.
What's special about this powder is that it can do something called "reduce" things. That means it can take away some of the oxygen from other things and make them into something else.
But don't go playing with this powder at home. It's really dangerous and can catch on fire! Scientists use it in special labs and with special equipment to do things like make medicines or make new kinds of molecules that can be used to treat diseases or make new chemicals.
So, that's basically what lithium aluminium hydride is. It's like a magic powder that we can use to make new things, but only if we're really careful and know what we're doing.