A system that is by-and-large self-maintaining in achieving its purpose.
Does it mean no more carbon emissions?
I wouldn’t think so, but it would mean understanding the cycle of such emissions, their impact, the extent to which any negative results are acceptable, and adjusting them accordingly.
Does it mean no more cars?
Probably not, but it may mean better engineering, fueling, and recycling.
Does it mean we all become vegetarians?
Again it means understanding the cycle, I doubt we would all need to be vegetarians but techniques in farming and the level of meat consumption may well need to change.
Does it mean we resurrect extinct species (should that become possible)?
I’m having a tough time of thinking of why that would be necessary as evolution is pretty good at filling gaps and I’m not sure we’d be able to do it without doing more damage than we fix. Though I suppose it could be possible if we’ve managed to wipe out a species whose niche turned out to be important enough and not being filled. On a personal level, yes it means demands resurrecting extinct species, mostly because I’m looking forward to mammoth rides and updates on megalodon sightings.