It's short for "composite" recording. As in, mixing several takes together to form a single one with the best bits of all of them.

Strictly speaking you can already do this using multiple tracks, but having a dedicated workflow will make it much easier.

Multiple takes intermixed on a single track. https://www.ableton.com/en/live/#comping

Recording different takes, and then piece different parts of those takes and create one final "perfect" take.