Presumirle comes from the verb presumir, which means 'to show off' or 'to brag'. In this song's romantic context, it's a sweet and proud declaration.
He sings, "Y presumirle a la gente que estoy enamorado" (And show off to people that I'm in love). He's not just happy to be in love; he's so proud that he wants the whole world to know, making this a unique and charming way to express affection.
This is the ultimate song for when you have a massive crush on someone and you're not afraid to show it. Ariel Camacho lays it all out, starting with the simple, direct title line, "Me gustas mucho" (I like you a lot). But he doesn't stop there. He quickly raises the stakes, saying he's willing to do anything for this person, even "Sacrificarme por un beso tuyo" (Sacrifice myself for a kiss from you). It's a huge, romantic declaration.
He's so into this person that he wants to "presumirle a la gente que estoy / Enamorado" (show off to people that I'm / In love). The song is a cascade of compliments, calling her "divina" (divine) and saying her smile fascinates him. It's a pure, sweet, and totally devoted love song, perfect for expressing feelings that are almost too big for words.