Súfrale is a colloquial and emphatic way of saying "Suffer!" or "Let them suffer!" It comes from the verb sufrir (to suffer) and adds the informal le to intensify the command, almost like saying "Go on and suffer!"
In this song, it's a key phrase where the singer, having been hurt, is now telling their ex-partner to experience the same pain and hardship they went through. It perfectly captures the theme of revenge and karma.
"Súfrale" is a breakup song built around one word: an old regional command that means something like "toughen up" or "deal with it." The singer isn't asking their ex to come back so much as ordering them to suffer the way they suffered. "Ojo por ojo, corazón por corazón" ["An eye for an eye, a heart for a heart"] sets the tone in the first real line, and the song barely lets up from there, running through everything the ex is about to lose sleep over.
What keeps it from turning into one long complaint is the second half, where Gloria Trevi shows up and the two artists start talking to each other by name instead of just singing at some absent ex. "Échale mi Gloria, Trevi" ["Go for it, my Gloria Trevi"] gets answered with "No que muy Firme" ["Weren't you so Firme"], a little joke on the band's own name, Grupo Firme. Trevi plays the one who isn't sure she's ready to let him off easy: "¿Sabes qué? Lo voy a pensar" ["You know what? I'm gonna think about it"], and that turns the track into a back-and-forth instead of a solo vent session. By the time the chorus rolls around again, súfrale has stopped sounding like advice and started sounding like a dare.