Fundamentally, magia in the UM-verse is a metaphor for the balance between community and selfhood. And the different schools of magia represent different approaches to community and self.
Energía mágica is a force, a power, born from connections between living beings. Energía mágica develops as connections develop. Once energía mágica exists, it can be called upon to perform different things.
In Audacia, the country where the story takes place, the most common schools of magia are: