Salvaje translates to "wild" or "savage." While it can describe untamed nature, in this song, it's used to describe a person's captivating and unrestrained demeanor.
Matt Hunter uses salvaje to portray a woman who is confident, independent, and has an untamed energy. Phrases like "flow salvaje" (wild flow) and "tiene eso así salvaje" (she has that wild thing) suggest an alluring and powerful personality that stands out from the crowd.
Matt Hunter's "Escala En Medellín" is all about a passionate, unforgettable connection. He's been thinking about this person all day, constantly having them on his mind. He remembers a cold February night when they were together, and she even let slip an "I love you" ("se te escapo un 'te quiero'") while they were getting intimate. It sounds like she couldn't get enough of him then, and now he wants to relive that whole experience, specifically making a "stopover in Medellín" ("Haciendo Escala en Medellín") to be with her again.
He's clearly smitten, focusing on the moment he was taking off her jeans ("Mientras te quitaba ese jean"). He doesn't care what anyone else thinks about her style, whether it's jeans or a short skirt; he just knows other people can't stand her because she's always doing her own thing. She's confident and knows what she has, describing her as having a "savage flow" ("flow salvaje") everywhere she goes. It's a fun, flirty song about wanting to repeat a wild, memorable encounter with someone who truly stands out.