Bambina literally translates to "little girl" or "baby girl." While it might seem like a common word, its repeated use in this song, especially in the iconic title "Ciao Ciao Bambina," gives it a unique and tender significance.
In the context of the song, it's used as an affectionate term of endearment for a loved one who is about to leave. It evokes a sense of innocence, vulnerability, and a poignant farewell, making it a memorable and emotionally charged word that is central to the song's theme.