Space is a vacuum, with no air molecules for sound waves to vibrate. Sound is a mechanical wave, and so it cannot travel through a vacuum. There are no air molecules in the vacuum that the sound wave can vibrate.
We can make it visual by thinking about a stadium full of people performing a stadium wave. The people are the air molecules, and they move — or vibrate — to keep the stadium wave going. Sound waves (the stadium wave) can move when there are air molecules (people). There are no air molecules (people) in a vacuum, so the sound wave cannot travel and make a noise, just as there is no stadium wave without people.