Crollerebbe comes from the verb "crollare," meaning to collapse or crumble. The conditional tense here, "crollerebbe," means "would collapse."
In the song, Mina sings, "Se non fosse per te crollerebbe il mio cielo" (If it weren't for you, my sky would collapse). It's a dramatic and evocative word that paints a vivid picture of emotional devastation, making it much more impactful than a simpler word like "fall" or "break."
This song is a powerful declaration of love and devotion. The singer expresses that their entire world revolves around one person, saying, "If it weren't for you, my sky would collapse." Without this person, they feel like nothing and can't even breathe. This love is a source of immense joy and clarity, making melancholy disappear and revealing the "only truth."
The core message is a grand promise. The singer pledges to do "everything a man can do" for their beloved. They see this person as the "queen of my desires" and the fulfillment of every possible dream. The lyrics paint a picture of a love that is all-encompassing, life-sustaining, and the ultimate quest, as important as crossing an ocean for a "woman's heart or a king's sword."