Any telescope, even the one Galileo used 400 years ago, efficiently collects the light from the universe, allowing us to see more clearly very distant and otherwise faint things. That light travels to our telescopes at the speed of light, and while very fast (300,000 km per second or 700 million miles per hour), it does take time to reach us from deep space. Sunlight takes a little over 8 minutes to reach Earth, the nearest star's light takes over 4 years to reach us, and from a distant galaxy it could take many millions of years to reach us. So we do see those distant galaxies as they appeared in the past, millions of years ago.