Q. What is it supposed to be on the show?

A. The 22nd Division police station.

 
Q. Where is it supposed to be on the show?

A.  In New York City.

Q. When did we see it on the show?

A. We see this location in at the very end of Episode 4 of Season 1 of Resurrection, and again at the very start of Episode 5.  
 
This is the NYPD station where homicide detectives Claudette Wallace and Melvin Oliva work. 
 
Harrison, after having a troubling discussion with Angel Batista, decides to turn himself in for the murder and dismemberment of Ryan, a hotel guest whom he killed during a fight to prevent  him from raping an unconscious girl.
 
In this scene, Harrison  is standing outside the station and is about to go in and confess, when suddenly a hand on his shoulder stops him. He is shocked to see that it belongs to Dexter, the father he thought he had shot and killed back in Iron Lake.

Q. What is it actually in real life?

A. A former city jail .

Q. Where can I find it in real life?

A. This is the former Yonkers City Jail, located at 24 Alexander Street, in Yonkers, New York. 

I'tt is located just half a block in from the Hudson River, between the railroad tracks and Hairs Park. 
 
This 10,000 square foot building was an active jail from 1926 until it was closed in 2013, as part of a city effort to transform the gritty waterfront area into a place for visitors.

Reports in 2014 were that the former jail was going to be transformed into an art studio and gallery, which could have aided the city's revitalization effort. But the buyer reneged on that deal  and decided to keep the building as a private gallery for his collection, not open to the public.
 
Here is a matching StreetView of the police station: 
 


Here is an aerial photo of the location.  And here is a map link.