Cenizas literally translates to 'ashes'. It is an evocative and poetic word that carries a lot of emotional weight in the Spanish language.
In the song, Bad Bunny quotes the famous Spanish proverb, "Donde hubo fuego, cenizas quedan" (Where there was fire, ashes remain), which means that past romances always leave lingering feelings. However, he cleverly twists this classic saying by declaring that he threw those ashes into the sea, proving that he is completely over his ex.
This is the ultimate post-breakup flex song. Bad Bunny is telling his ex that not only is he over her, but his life is way better now. He's not subtle about it either, listing off all the new things he has: "Con la baby nueva, con los carros nuevos / Con la combi nueva, con piquete nuevo" (With the new girl, the new cars / With the new outfit, with the new swag). He insists he's not in pain anymore, saying "Te juro que ya no me duele, no me duele" (I swear it doesn't hurt me anymore, it doesn't hurt).
He spends the whole song basically laughing at the idea that he might be sad. He tells his ex that if she thinks he's suffering, she clearly hasn't seen him out partying. He's pretty blunt, telling her "No es que no te quiera, es que ya no quiero" (It's not that I didn't love you, it's that I don't want to anymore). He even wishes her the best, but with a twist: "Yo te deseo el bien, te deseo lo mejor / Y lo mejor ya te pasó" (I wish you well, I wish you the best / And the best thing already happened to you), meaning, of course, him. It's a classic Reggaeton track about moving on and letting everyone know you've upgraded.