How work the gyro when a skill is selected ?

I work on color detection and I want to stay in a certain position. In the main program, i oberved when i send for exemple "ksit" in the serial monitor and i stress the dog, it use the gyro to stay in the position selected. How it works ? Where is the magic programing tricks ? I search but for the moment, i didn't undersand how it does works ! Can you help me ?