Where my finger is pointing, can someone please tell me what vacuum line goes here? Or what sensor it even is? Thank you

 

Need a picture from farther out can really see where it is in the engine bay

 

this is the best picture I got....

 

That is not a vacuum line.

 

Yes, not a vacuum connection, that's the rod that's connected to the Vacuum "motor's" shaft for the Heater hose by-pass
The larger black cylinder is the Vacuum "motor"/valve, you can see its vacuum hose connected at the opposite end of the shaft/rod connection
90deg vacuum hose connector and a grey vacuum hose that runs to the firewall and into the cab

This is only used if AC MAX is selected in the cab, or OFF, it cuts off coolant flow thru the heater core in the cab, not used for temp control, thats done by the Blend Door inside the cab