Yep, swing is usually used to add variation to your beats. Basically what's happening is that the midi or audio affected by a certain amount of "swing" will be slightly moved from their original position. That will result in a more "human" playback timing, giving your beat ( or other instruments ) a different groove.
For Midi you can just select the regions or notes you want to affect and use the "Swing" amount value paired with the Q-Strenght ( Quantization Strenght ) value, it's set to max 100 by default.
For applying swing to Audio Tracks, check this Tech-Tip from Chris here :