At it's most basic level, when people are looking for "Environments" it is generally referring to multi instrument objects with patch names already setup to correspond to their hardware.
So if, for example, you are using a Roland JV 2080 synth, a basic 2080 environment would include a multi instrument with patch lists for all the banks, plus some custom bank messages for moving between banks. That way you can see the specific patch names when loading in patches.
That's a basic use of the Environment. One step up from that would be objects to control other aspects of the hardware. maybe some sysex faders to control internal patch parameters like envelopes or LFOs, etc. Maybe some MIDI CC faders to control the effects processing values on the patch, etc. It might include a small MIDI mixer if the hardware is used multitimbrally. It of course depends on the hardware.
Anyway, that's one general old school use of the Environment.