Narcótico translates to "narcotic" in English. It's an intriguing word choice because it directly compares the feeling of love or attraction to the powerful, addictive effect of a drug.
In the song, Tito El Bambino sings, "Eres amor narcótico" (You are narcotic love), implying that the person's presence is intoxicating and irresistible, much like a narcotic. This strong metaphor makes the word stand out and adds an intense, almost dangerous, allure to the romantic connection described.
This is a reggaeton slow-burn about pure, mutual attraction, and Tito El Bambino does not dress it up. The hook says it straight: "Se me daña la mente cada vez que te veo" (My mind gets wrecked every time I see you). Dañar normally means "to damage", so the idea is that just seeing her breaks his brain a little.
He piles on the chemistry talk: "Es que tienes química, eres amor narcótico" (It's that you've got chemistry, you're a narcotic love). Then comes a sneaky secret-affair verse: "Nadie sospecha de lo que yo hago contigo" (Nobody suspects what I do with you) and "Para la gente sólo somos más que amigo'" (To people we're just more than friends). Notice amigo': the dropped final s is very Puerto Rican, so it is really amigos. The line "me pones mal" (you get me bad) is a casual way of saying she drives him crazy.
The outro is pure name-dropping: Mambo Kingz are the producers, El Patrón is Tito's own nickname, and Dios los bendiga (God bless you all) is his usual sign-off.