It’s German for crank-angle. Meaning, the relationship between the rotation of the crank and cam, expressed in degrees. So 1.0 KW would mean the crankshaft is rotated one degree ahead of the camshaft. Refer to video above.
The further out of adjustment it is, the worse the engine will run. This could vary from barely noticeable, all the way to not running at all, and anything in between.