Candela literally means "candle" or "fire," but in many Latin American contexts, especially in urban slang, it's used to describe a situation that is intense, dangerous, or even "on fire" with excitement or trouble.
In this song, J Balvin warns, "Cuidado con la calle, que está candela" (Be careful with the street, it's candela). Here, it implies that the streets are dangerous, hot with activity, or full of potential trouble, making it a vivid and engaging word choice.
Stormzy takes the mic first, in English, and doesn't bother easing in: "Tell man once, don't cross my wires" is a warning dressed up as a boast, and by the time he gets to "Mike Jordan, Jackson or Myers" he's already run through three separate icons just to describe himself. It's the kind of opening a UK grime verse does well, all confidence and short lines, before the beat drops into Spanish and J Balvin takes the room over completely.
His hook is a party trick repeated until it sticks: "¿qué lo que? ¿Pa'ónde vas? ¿Qué tú haces?" [What's good? Where are you going? What are you doing?] is less a question than an excuse to talk to whoever just walked by, and "Hoy la casa invita, todas las gatas que pasen" [Today it's on the house, every babe who passes] makes the whole song feel like an open door. Later he switches from the club to the block, pairing "Barrio libre como Mandela" [A neighborhood free like Mandela] with "Muhammad Ali tirándote un jab" [Muhammad Ali throwing you a jab], a freedom fighter and a boxer named in the same two lines, like they're just more comparisons for how he moves.