Manes Hideout is a beginner grind-zone. Manes mobs are primarily fought for quest-related reasons. The xp here is low but the money is decent for a newer player. With that being said, this spot is okay very early on, but you should focus on questing until you reach level 56 - once level 56, you can grind Polly's for better, more profitable rewards.
Manes Hideout is located east of Heidel; Heidel is south of Velia, Black Desert's first major city when you start the game.