Pull-offs are an efficient way to play a series of notes or musical phrases quickly. The idea is to pick the string once, but play two (or more) notes. It’s not just for efficiency though. And it’s not necessarily a workaround for faster playing. Pull-offs add a lot of style and nuance. You can even add them to chords and progressions!
For best results, pull down towards the ground instead of up away from the fretboard. This will let the next note ring louder when you pull off.