Dresser literally means "to train" or "to tame" an animal. It's an interesting word choice because it's not commonly used in everyday conversation or many song lyrics.
In the context of the song, the artist sings, "J'suis le loup sauvage qu'on n'peut pas dresser" (I'm the wild wolf that cannot be tamed). This powerful metaphor highlights his untamed, independent nature, making dresser a key word to understand his self-perception.
"Loup" is Captaine Roshi and So La Lune's gritty street anthem, built around the image of a wolf that refuses to be tamed. Roshi raps about hustling, staying loyal to his crew, and the price of chasing money and respect on his own terms, running under the moon as a pirate and an outlaw.
Under the bravado sits a quieter thread of regret. The recurring line "I had my reasons if I left you" points to a relationship he walked away from for the life he chose, and the song closes on that tension between the freedom he's found and what it cost him.