I've fixed something like that before with an underwater epoxy and silicone tape from walmart just to limp home from the middle of nowhere. (please don't do this)
I'd guess it goes to the heater, but I can't find anything like it for the HVAC or Coolant systems on
Courtesy Parts.
I feel like it may be the lower left (in the illustration) hose here
https://www.z1motorsports.com/z1-sil...et-p-5202.html