Mystery plug on Honda Generator

It's the amps not the volts.

It's either 120 or 120/240.

My generator is a 5000/6250 watt. (5000 continuous, 6250 startup/surge).

More than enough to run the frige and a window unit AC plus a couple fans and a few rooms of lights.
(frige and window AC should be on different phases)

...the 20 or 30 amp rating of the connector theoretically limits you if using #10 wire, but using #8 wire will help.

Startup draw of compressors is the true limiting factor.