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

A. A wig store.

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. In Episode 8 of Season One of Resurrection.
 
When we first  see this wig shop, Dexter notes a sign in the window saying that the owners are on vacation and the store will be closed while they are gone. He sees it as a perfect place to kill Al Walker, the serial killer known as “Rapunzel” (because he cuts the ponytails off his female victims) . 
 
But when his plans to kill Al fall through, he improvises and uses the kill room he had prepared to scare Elsa's abusive landlord into doing the right thing. he kept pulling on a stocking mask, Dexter kidnaps Vinny, ties him to his kill table, and terrorizes him with threats of death if he doesn't start treating his tenants decently.
 
Vinny doesn't respond to empathetic appeals from his tenants, but death threats are a language he understands, especially when he's strapped to a kill table a masked lunatic about plunge a knife into his heart.

But unbeknownst to Dexter, Angel Batista has slipped a tracking device into his car, has followed him to the wig shop,  and is about to intrude on this scenario.  Dexter hears Angel coming, cuts Vinny loose, and beats a hasty retreat. 

Running out, the terrified Vinny runs right over Angel, buying Dexter a few seconds to escape.

Angel enters the kill room, only to find it empty, but draped in the usual plastic sheeting that Dexter uses for his rituals.The
 
 Angel recognizes the M.O. of the Bay Harbor Butcher, and calls the cops, sure that he finally has proof that Dexter is killing again as the BHB.

But when the Detectives Wallace and Oliva arrive, they find nothing but an empty room draped in plastic. No victim, no suspect, no witnesses...

When Angel insists that Dexter is the Bay Harbor Butcher, they begin to suspect that he may have draped the room in plastic himself, in order to prove his allegations, and the encounter leaves him feeling foolish and frustrated.

Q. What is it actually in real life?

A. An actual wig store.

Q. Where can I find it in real life?

A. This is “Wigs and Plus”, located at 37 W. 14th St., in New York's Flatiron District.

( It's located eight blocks south of the Flatiron Building.)
 
They actually shot the scene inside the wig store.

You’ll find their website at www.wigsandplus.com.

( They also shot the scene of Angel Batista leaving a subway and walking towards the store, on this same street. )   


Here is a matching StreetView of the wig shop: 
 


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