Acicalá' is a colloquial, shortened form of "acicalada," meaning "dolled up" or "spruced up." It refers to someone who has taken great care to groom themselves and look their best.
In the song, it describes a woman who is always well-dressed and ready to go out, setting the scene for her independent and carefree lifestyle. It's an engaging word that paints a vivid picture of someone ready for a night out.
"Sin GPS" is Tony Dize's excuse for not needing directions: he already knows exactly where he's headed. The hook says it straight, "Sin GPS voy manejando / Hacia el camino de tus labios" [I'm driving with no GPS, toward the path of your lips], and that's the whole song in one line, a pickup dressed up as a road trip.
The girl he's chasing just got out of something and isn't sitting home over it: "Ella ya no está despechada / Desde que se dejó no le importa" [She's not heartbroken anymore, since she broke up she doesn't care]. He rolls up with the car and the tinted windows, invites her to bring a friend, and by the second verse it stops being subtle at all: "Cambió el ambiente, parece un porno casting" [the vibe changed, it looks like a p*rn casting]. This is a backseat song, not a highway one.