Uhh it stands for host bus adapter I think. It’s the word for a sas add on card. They make about a million different kinds that are all secretly the same card and just have different numbers of plugs, location of plugs, card dimensions or interfaces and support different protocol versions.

An hba will let you plug up to any sas thingy and talk to it. If that thingy is an enclosure then all the drives in the enclosure will be directly addressable as if they were directly plugged into your hba inside your computer instead of connected to your computer by a wire.

Sata is physically and electrically one way backwards compatible with sas, so a Sata drive can plug into a sas enclosure but the reverse isn’t true.