This is a classic vallenato kiss-off from Binomio De Oro, and the singer starts from a very high place: "Te tenía en un pedestal" (I had you on a pedestal). She owned his luck, but he could never tell whether she actually cared about him. Over time the feeling faded, because he noticed "que yo nadita te importaba" (that I didn't matter to you one little bit). Nadita is the cute diminutive of nada, and here it stings more than a plain "nothing" would.
Then he gets a bit smug. "Y menos mal que soy un hombre juga'o" (and luckily I'm an experienced man): jugado is Caribbean slang for someone who has been around and can't be fooled, so he spotted her jugada (move, trick) from a mile off. The chorus asks "Cómo pretendes engañarme a mí" (how do you expect to fool me), and the title line is blunt: "Lo que no sirve se bota, es una ley de la vida" (what doesn't work gets thrown out, it's a law of life). The best part? He says she was the one who taught him that rule: "me lo dijiste tú un día" (you told me so one day).
His plan to avoid more pain is very practical: "Mejor enamoro a otra" (I'd better make someone else fall for me). There's a gentler moment too, "El amor es un jardín que tiene distintas flores" (love is a garden with different flowers), before he admits the whole thing was "un espejismo" (a mirage).