What does velocity tell about movement

Velocity tells you what speed a moving object travels at and in what direction.

Velocity is object's movement but it has direction because it's a vector! 

Sounds propagates through some kind of medium. usually it's air, but it goes just as well through solid objects like walls, windows etc. a soundwave will compress the (air)molecules in front of it, and if this increased density wave hits your ears, you register it as sound. solid objects like walls are a lot denser than air, this means that they will damp a wave, but also carry it easier.