Asesino literally translates to "killer" or "assassin". It's a strong and unexpected word to find in a reggaeton song, making it particularly memorable.
In the context of "No Quiero Amarte," Justin Quiles uses asesino metaphorically. He sings, "En esta escena seré tu asesino" (In this scene, I will be your killer), implying he will be so captivating and intense that he will metaphorically
The hook is a scheduling problem. «Yo no quiero amarte» (I do not want to love you), Justin Quiles says, and then explains what he does want instead: «Quiero recogerte un viernes y entregarte un martes» (I want to pick you up on a Friday and drop you off on a Tuesday). Four days, returned by Tuesday. It is a blunt way to put it, and the whole song runs on how badly the rest of the lyrics contradict it.
Because he keeps describing something that sounds a lot like love. He wants «conocer más allá de tu timidez» (to know what is beyond your shyness), he has noticed «que tienes un lado oscuro» (that you have a dark side), and by the second verse Zion & Lennox are offering wine and a second date: «Dos copas de vino y un Franco de Vita» (two glasses of wine and some Franco de Vita), a Venezuelan balladeer whose songs are the opposite of casual. Then «Hoy tú y yo cambiaremos el destino» (today you and I will change our fate). That is not a four-day plan. The refrain never admits it.