What does zone mean in sound levels

a "zone" is used by amplifier manufacturers who intend for their amplifiers to be able to power speakers in multiple rooms and from mixed audio sources. A "zone" is really just a fancy way of saying "room" without implying the existence of floor to ceiling walls because a zone could very easily be an outdoor patio.

So if you see 0.5 "zones" then that's about a half of a room

Ah, now that makes more sense

As an engineer I hate it already