Fina is an adjective that means "fine," "classy," or "refined." It's typically used to describe someone or something that is elegant and sophisticated.
In this song, Bad Bunny and Young Miko use the word ironically. They describe a woman who is both "fina" and sexually liberated, challenging the idea that a classy woman must be reserved. The song's hook suggests that true class lies in confidence and freedom, making this a very interesting and modern use of the word.
Bad Bunny and Young Miko team up on "FINA" to celebrate wealthy, wild women who do whatever they want without caring about gossip. Bad Bunny opens the track with explicit humor, comparing himself to the cartoon character Caillou ("Tengo el bicho afeitado y cabezón como Caillou" [I have my dick shaved and big-headed like Caillou]) and sneaking into a Gucci fitting room ("vamos pa' la Gucci pa' hacerlo en el probador" [let's go to Gucci to do it in the fitting room]). The hook flips polite expectations upside down: "Si las más putas son las más finas" (If the freakiest girls are the classiest ones). It praises women who stay classy in public while being completely uninhibited in private.
Young Miko delivers sharp Puerto Rican slang, shouting out the beloved Puerto Rican bakery chain Ricomini when she describes a girl from the island's west coast: "Es de west, bizcochita, 'tá Ricomini" (She's from the west, a little cake, looking tasty like Ricomini). She also jokes about throwing her phone number onto a plush Dr. Simi doll ("Me dejó el número de teléfono en el Dr. Simi" [She left me the phone number on the Dr. Simi]), nodding to the Latin American concert craze of tossing the mascot on stage. By the end, both artists encourage independent women to focus on their own money instead of settling down: "Háblale de tickets, no le hables de boda" (Talk to her about money, don't talk to her about weddings).