Deleito is a beautiful, poetic word that means "I delight" or "I take great pleasure in". It comes from the verb deleitar and is a much more expressive way to say you enjoy something than the common me gusta (I like).
In the song, J Balvin is tired of arguing and tells his partner, "Baila, que yo me deleito" (Dance, because I delight). He's saying that watching her dance brings him immense joy, a feeling so strong that this special word is needed to capture it.
This song is all about a relationship that's stuck in a cycle of fighting. J Balvin and Bad Bunny sound completely fed up, singing, "Trato, trato y queda en nada / Peleamos otra vez" (I try, I try and it comes to nothing / We fight again). The communication is on and off, and they feel like they're being treated "Como un bebé" (Like a baby). They're just tired of the drama and want a simple solution.
Instead of talking things out, their answer is to forget the arguments and focus on something else entirely. They plead, "solo dame un break, break, break" (just give me a break, break, break) and then switch gears to a simple command: "baila pa' mí" (dance for me). Bad Bunny is even more direct about it, saying he's not in the mood to argue and would rather she just dance. It's a fun, catchy track that basically says, "Let's stop fighting and just dance instead."