During the development of the "Return to Jurassic Park" DLC I was responsible for finalizing this building based on a block-out provided by one of our outsource partners.
In game the Hatchery is the location where you incubate and hatch the dinosaurs, this functions a little bit different in the dlc than it does in the main game as it is only placed in a specific campaign mission on a different island, in sandbox it functions like normal.