Salir por piernas is a fun Spanish idiom that literally translates to "to leave by legs". Its real meaning is to run away, bolt, or flee from a difficult situation.
In the song, Alvaro Soler describes himself as the kind of guy "que no se sale por piernas"—one who doesn't run for it. He's making a statement that he's loyal and dependable, someone who will stick around through thick and thin, unlike someone who might flee at the first sign of trouble.
Have you ever felt like you're not the coolest person in the room? Alvaro Soler gets it. In "Tipo Normal," he celebrates being a completely regular guy who somehow won over an amazing, and very different, person. He lays it all out: "Tú y yo somos diferentes / Como la noche y el día" (You and I are different / Like night and day). She likes reggaetón, he prefers poetry. He's in a t-shirt, she's wearing Chanel. He's a simple, classic romantic who opens doors and kisses her good morning.
He's not trying to be anyone else. He admits, "Yo no tengo tatuajes, tampoco sé bailar" (I don't have tattoos, I don't know how to dance either). But that's the whole point! He's proud of being a normal guy, because that's exactly what she fell for. He might not be a flashy dancer (unless he's had a few drinks!), but he promises loyalty and makes her feel incredible. It's a fun, sweet song about how you don't need to be extraordinary to have an amazing connection with someone.