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.
This song is a total anthem for anyone who's been cheated on! Ozuna tells the story of a woman who finds out her boyfriend was unfaithful, or as he puts it, "su novio a ella la engañaba, como si nada" [her boyfriend cheated on her, like it was nothing]. But instead of staying home and crying, she decides to get her revenge by living her best life. She gets all dressed up, calls her friend, and goes out to party.
She's completely over the guy who "mató su sentimiento" [killed her feelings] with empty promises. Now, "ella hace lo que quiera" [she does whatever she wants]. The song follows her on her night out: she's driving fast, dancing to great music, and drinking champagne. The narrator, Ozuna, sees her at the club and thinks her ex is a fool for losing her. It's a classic story of turning heartbreak into a powerful, fun night out with your friends.