Ernesto knows his stuff. This is a throwback to the era of hotel casinos when they had grooming stations for men located on site to keep you looking fresh after a night of drinking and gambling downstairs.
The space itself is just an old hotel room at the end of the hall that has been converted into a barber shop. Nothing fancy, just a small waiting area with a small TV, and one chair for hair cuts.
Finding this place can be a little challenging; go over by the craps tables, and there's a staircase that leads upstairs to the hotel rooms: that's the one you need to take.