It cannot travel through vacuum because sound travels by producing a vibration in the molecules of the medium surrounding it. And there are virtually no molecules in vacuum.
When a body produces sound it produces vibrations. These vibrations cause the medium molecules (air, water or solid) to vibrate.
As the sound wave propagates, the molecules themselves do not move from one point to another, they only vibrate at the mean position. It is the effect that propagates and reaches our ears.
