It is most likely similar to the Grillby's in Undertale, except the monsters are not friendly towards each other. A known monster that goes to Grillby's is Sans because he and Grillby are friendly with each other. Papyrus comes here too,unlike Papyrus' Undertale Counter-Part, in which he doesn't go to Grillby's. The order is sometimes messed up when you order here, and chances are the bar burns.
This is also where Sans takes Frisk on their first date.