The RPIC, or Remote Pilot In Command is the sole person responsible for the operation of a sUAS. The term derives from the manned aircraft version: Pilot In Command, or PIC. The RPIC may only fly one aircraft at a time and must either hold a remote pilot airman certificate with a sUAS rating or be under the direct supervision of a person who does hold a remote pilot certificate (remote pilot in command).
You can read more about the requirements at Part 107 Summary.