Neverita is the diminutive form of nevera, meaning "refrigerator" or "cooler", so it literally translates to "little cooler". The -ita suffix is a common way to make things sound smaller or more affectionate in Spanish.
In the song's key line, "El corazón lo puso en la neverita" (She put her heart in the little cooler), the word is a powerful metaphor. It means she has decided to keep her heart and emotions "on ice", choosing to be emotionally guarded and unavailable.
It's a very creative and memorable piece of modern slang that perfectly captures the song's theme of protecting yourself from heartbreak.
Bad Bunny is crushing hard here, but the girl he likes is not making it easy. He wants to be with her, singing "Yo estoy puesto pa' ti / Y tú te me quitas" ("I'm ready for you / And you pull away from me"). She has put her heart on ice for the season—literally "en la neverita" ("in the little cooler")—and decided to stay single all summer. Still, that does not mean she is lonely. Her inbox is flooded with messages ("El DM explotado"), and there is a whole line of guys waiting for her attention. Bad Bunny even jokes that she treats him like a joke, pleading "me tienes de meme" ("you've got me looking like a meme").
Puerto Rican slang really brings the beach setting to life throughout the track. When he shouts "Diablo, qué piquete la chamaquita" ("Damn, what swagger the young girl has"), he uses piquete to describe her cool confidence and chamaquita for a young woman. Instead of giving up, he keeps trying everyday summer pick-up moves. He offers to apply her sunscreen ("sunblock"), grab her a beer, and just hang out watching TikTok videos ("viendo TikTok"). It is a playful, self-deprecating track about chasing someone who is having far too much fun keeping her options open.