That is an abbreviation for Collective Cyclic Pitch Mixing. To simplify, it is any control system that has the swashplate do both - it moves up and down for collective and tilts for the cyclic, then it is a CCPM system.

There are/where that used a swashplate that did not move up and down (e.g. the older Schluter Kalt, TSK and Kyosho competition helis) for collective. It only tilted to deliver cyclic commands to the rotor head. The collective was delivered by another control system that moves the washout hub or flybar up and and down seperately.

To further describe the CCPM type, there are two.

One classified as eCCPM, which uses three or four servos working together, and software inside the TX, to mix their commands so they will move the swashplate up and down for collective and tilt it for the cyclic.

The other is classified as the mCCPM system, which uses a single servo dedicated to follow only one command, and the mixing is done mechanically, by a more mechanical control system built into the heli mechanics.