Space suits protect astronauts by keeping out extreme temperatures, they are also strong enough to protect astronauts from getting hit by space dust. Additionally they supply oxygen and water.
Also, the visor thing on the helmet, I think it's called a solar shield, protects the astronaut from the sun's harmful rays; think staring at the Sun from Earth is bad? I think staring at the Sun from outer space wouldn't be pleasant... these "powerful sunglasses" help you keep your sight. :) Hope this helped!
