Arrecha is a fascinating and versatile slang term in some Spanish-speaking countries, particularly Colombia, where Ryan Castro is from. While it can mean 'horny' or 'turned on,' it also commonly means 'angry' or 'fed up.'
In this song, the line "Cuéntale cuando estabas arrecha" (Tell him when you were arrecha) plays on this double meaning. It could imply a moment of intense passion or a moment of intense frustration, adding a layer of intrigue and rawness to the lyrics that is very characteristic of reggaeton and urban music.
Ryan Castro opens this one at midnight with a bottle for company. "Las horas del reloj marcan las doce" [The hands of the clock strike twelve], he sings, thinking about an old love who still "me conoce" [knows me] and still "me mata, y me mata de dolor" [kills me, and kills me with pain]. He gave everything to make it last, and now she looks straight through him: "Mírame a la cara y dime que no me conoces" [Look me in the face and tell me you don't know me].
Then the song does something salsa loves to do with a broken heart: it turns the wound into a toast. "Esta canción va dedicada" [This song is dedicated] to, as he puts it, "Para todas esas personas que creen en el amor" [everyone who still believes in love] and got burned anyway, right before the beat opens up into full salsa and Ryan yells "¡Salsa!" like he's starting a party instead of ending one. From there the record flips: he's single, he's making money, and Cupid can forget it, "Cupido ya no me acecha, no tiene flechas" [Cupid doesn't stalk me anymore, he's out of arrows]. It closes the way a lot of collab tracks do, with everyone shouting their own name into the mic: he made her "una canción con la receta de COQE" [a song with COQE's recipe], gives a shoutout to "Kapo del más buscado" [Kapo, the most wanted], and hands the last word to his featured singer with one line, "¡La ETERNA!" [The eternal one!], which is her name as much as it is a boast.