Plain English Meaning
Working through the checklist steps to figure out why the generator stopped producing electricity and trying to bring it back online before the battery runs down.
Full Definition
The pilot action of identifying the cause of a failed generator (or alternator) and attempting to restore electrical output through a defined sequence of steps — typically checking circuit breakers, cycling the generator switch, verifying bus voltage, and reducing electrical load — in accordance with the aircraft's Pilot's Operating Handbook (POH) or Aircraft Flight Manual (AFM) .