Rob,
HMLA is the USMC designation for an attack helicopter unit. It is simply H - Helicopter, M- Marine, L- Light, A- Attack. HMLA-369 was the original AH-1J Sea Cobra unit that first saw combat in Southeast Asia in 1971. Cool history. I'm sure some of the other members like SuperCobra could fill you in more on the USMC end of things.
No need to apologize, we're all learning here! You're in the right place!