Capítulo literally translates to "chapter," like in a book. It's an interesting word choice because it frames the romantic encounter as a developing story.
In the song, Yandel uses it to suggest continuing or starting a new phase in a relationship, singing "vamos a darle otro capítulo" (let's give it another chapter) and "Necesito otro capítulo, bebé, de mucha acción, travesura'" (I need another chapter, baby, with lots of action, mischief). This gives a sense of progression and excitement to the romantic narrative.
Get ready to feel the heat with Yandel's "CAPITULO"! This song is all about that electrifying moment when you're out, feeling yourself, and someone catches your eye. Yandel is totally captivated, seeing this person with their "maquillaje y ese piquete cabrón" [makeup and that awesome swagger], and he knows everyone else is looking too, "Todos te están mirando y deseándote" [Everyone is looking at you and desiring you].
He's basically saying, "I want everything I'm thinking to happen," and he can already tell by their body language that they're on the same page. He's inviting them to take things to the next level, to start "otro capítulo" [another chapter] because this night is just getting better and better. He's confident, a little playful, and definitely ready to make a move, even hinting at a playful "arresto" [arrest] if they want to feel it again. It's a fun, flirty track about seizing the moment and letting loose!