Kryptonita is the Spanish word for 'Kryptonite', the fictional substance from the Superman comics that can weaken the otherwise invincible hero.
In this song, the singer uses it as a powerful metaphor for love. He sings, "Para ser alguien fuerte se volvió mi kryptonita" (To be someone strong, she became my kryptonite), expressing that this person is his one and only weakness. It's a modern and clever way to say you're completely captivated by someone.
This song is a full-on declaration of love and obsession for one special person. The singer is completely captivated, comparing her to his kryptonite—the one thing that can make a strong person weak. He says, "Para ser alguien fuerte se volvió mi kryptonita" (To be someone strong, she became my kryptonite), but he still needs her completely.
He's not shy about his feelings, mixing sweet compliments with bold, pop-culture-filled lines. One moment he's comparing himself to Goku from Dragon Ball Z, "Me siento Kakaroto en la nube que flota" (I feel like Kakarot on the floating cloud), and the next he's asking her to be his goddess. He loves everything about her, from her pink dress and long hair to her personality, which he says "se sacó un 10 en su nota" (got a 10 on its grade). It's a fun, slightly over-the-top love song about being so into someone that they completely dominate your world.