Answer:
Sound, like light or heat, is a wave. However, one major distinction is that, unlike light or heat (radiation), sound needs a medium to travel. Sounds require the presence of molecules or particles to travel from one region to another.
Explanation: I don't know if yours came with pre-answers, but this is what I put because I'm assuming it didn't.
Space doesn't have many molecules or particles to travel. That is how, sound gets around, if space doesn't have the molecules or particles, that'll cause it not to have sound! ^^ Hope this helps, luv!