Calladita is the diminutive form of callada, which means "quiet". The -ita suffix is very common in Spanish and adds a sense of smallness or affection, so the word translates to "the little quiet one" or more naturally, "the quiet one".
This word is the key to the entire song. Bad Bunny describes a woman who appears shy and reserved on the outside, a calladita, but reveals she has a hidden wild and daring (atrevida) side. The song's whole story plays on this contrast, making calladita a memorable word that captures the central theme of hidden depths.
Bad Bunny's "Callaita" is all about a woman who seems one way on the surface but is completely different underneath. The title itself means 'the quiet one'. The song describes her as someone who is supposed to be studying but instead calls her friend to go party, or janguear. She's described as calladita [quiet], but when it comes to sex, she's atrevida [daring]. She's just out there gozándose la vida, como es [enjoying life, as it should be] with weed and drinks.
But there's a story behind her new attitude. Bad Bunny wonders what happened to her, singing Ella no era así, no sé quién la dañó [She wasn't like this, I don't know who hurt her]. It seems a recent breakup has given her a vida nueva [new life]. Now she hangs out with a friend who's like her girlfriend, leaves her fear in a drawer, and lives by a simple, fun-loving formula: Si hay sol, hay playa / Si hay playa, hay alcohol / Si hay alcohol, hay sexo / Si es contigo, mejor [If there's sun, there's beach / If there's beach, there's alcohol / If there's alcohol, there's sex / If it's with you, even better]. The song celebrates her liberation and finding a new way to enjoy herself, even if it's a bit wild.