This is the FIMily version of Zecora. In this universe, Queen Helia keeps all the old villains and monsters she and her sisters turned to stone in a statue garden in the forest of monsters. Subira here is the warden there.

Prisoners with life sentences are given the choice to go serve as guards in the forest of monsters for a reduced sentence. It's dangerous work and deaths aren't unheard of, but as long as they listen to Subira and do as they're told, they're usually fine.
Most new guards are intimated by her, but to the ones who've lived in the forest a while she's seen as a protective and well respected mother figure.