"Puñaladitas" is the diminutive form of puñalada, which means "a stab". The literal translation is "little stabs" or "little backstabs".
In the song, ROSALÍA uses this unique word to describe the nature of fame's ambition. She sings, "Puñaladitas da su ambición" ("Its ambition gives little stabs"), powerfully illustrating how the desire for fame inflicts small, sharp, and constant emotional wounds. It's a memorable image of the painful side of celebrity.