Prende en candela literally translates to "catches on fire". It's a fiery and energetic slang expression you'll often hear in Caribbean Spanish and reggaeton music.
In this song, Ozuna uses it to describe how the woman comes alive on the dance floor. When the champagne and good music hit, she "gets lit" or becomes the life of the party, full of unstoppable energy. It's the perfect phrase to capture the feeling of letting loose and having an amazing night out.
Puerto Rican superstar Ozuna brings the ultimate post-breakup energy in "Se Preparó". Instead of staying home to cry over an unfaithful ex, the protagonist decides the best revenge is living her best life. The chorus lays it all out right away: "Se preparó, se puso linda, a su amiga llamaba / Salió de rumba, nada le importó" ("She got ready, made herself pretty, called her friend / Went out to party, didn't care about anything"). Her boyfriend cheated on her "como si nada" ("like it was nothing"), so she traded tears for a wild night out.
Ozuna watches her take total control of her freedom. He sings that "Hoy ella hace lo que quiera / Se monta en su nave, a quemar la carretera" ("Today she does whatever she wants / She gets in her ride, to burn up the highway"). In Puerto Rican slang, calling a car a "nave" (literally a "ship" or "spaceship") means it is a slick, fast ride. Once she hits the club with her crew, she leaves the past behind with good music and champagne, proving her ex was a "bobo" ("fool") for throwing away what he had.