Candela literally means "candle" or "fire". However, in many Latin American contexts, especially in urban music, it's used as slang to describe something or someone as "hot," "intense," or "on fire."
In this song, when De La Ghetto sings "Ella está candela," he's not talking about a literal candle. He's using candela to describe the woman as incredibly attractive, passionate, and full of energy, making her irresistible.
De La Ghetto's "Lo Que Me Falta" is all about that intense, immediate attraction when you meet someone who just gets you. He's feeling a little crazy, and she's "loquita" [a little crazy] too, so it's a perfect match! He's confident that "Lo que es mío nadie me lo quita" [No one takes what's mine from me], and he's ready to make his move.
He's super drawn to her free spirit, saying she has "buena vibra" [good vibes] and "Anda paseando libre por la vida" [goes around freely through life]. But he's also determined to change that solo status, because "Se va a acabar" [It's going to end]! For him, she has "todo lo que me falta" [everything I'm missing], and he's already got the romantic setup ready: "Tengo la cama cubierta con pétalos" [I have the bed covered with petals] to seal the deal. It's a fun, flirty track about a guy who knows what he wants and isn't afraid to go for it!