Red's was the hub of social activity aboard the USS Discovery-A. It was a lounge with a bar and a central fireplace where crewmembers could socialize and have meals. (DIS: "Jinaal")
Commander Jett Reno would pick up guest shifts as a bartender at Red's. (DIS: "Erigah")
Though seen in earlier episodes of Star Trek: Discovery, the place was not named until the fifth season episode "Jinaal".