A kite rig is a way to launch a kite into the air and make it fly. It involves attaching a string or rope to the kite's frame and then attaching the other end of the string to a spool that you spin. As you spin the spool, it spools up the string and pulls on the kite. This makes the kite lift into the air, and you can then let go of the spool and the kite will keep flying.