https://www.liveabout.com/nessun-dorma-lyrics-724333
Context
At the beginning of the opera, which is set in Peking, China, Calaf, an unknown prince, falls in love at first sight with the beautiful but haughty Princess Turandot. According to royal edict, however, any suitor who wishes to marry her must correctly answer three riddles. Those who fail are killed. Despite protests from his father and his servant, Calaf accepts the challenge and is determined to marry Turandot.
Much to the delight of the princess's father, as well as the entire kingdom, Calaf answers all three riddles correctly. But Turandot refuses to marry this stranger. She doesn't even know his name. The prince then makes a deal with her: If she can figure out his name before dawn, he will gladly die. If she cannot, they will marry. Turandot agrees and the countdown begins.
Late that night, the princess declares that no one will sleep until she learns the name of her suitor. In fact, she cries out that everyone in the kingdom will be killed if no one steps forward to reveal Calaf's identity. Meanwhile, Calaf confidently sings "Nessun Dorma"—"Nobody shall sleep."
Italian Text
Nessun dorma! Nessun dorma!
Tu pure, o, Principessa,
nella tua fredda stanza,
guardi le stelle
che tremano d'amore
e di speranza.
Ma il mio mistero è chiuso in me,
il nome mio nessun saprà!
No, no, sulla tua bocca lo dirò
quando la luce splenderà!
Ed il mio bacio scioglierà il silenzio
che ti fa mia!
(Il nome suo nessun saprà!…
e noi dovrem, ahime, morir!)
Dilegua, o notte!
Tramontate, stelle!
Tramontate, stelle!
All'alba vincerò!
vincerò, vincerò!
English Translation
Nobody shall sleep!…
Nobody shall sleep!
Even you, oh Princess,
in your cold room,
watch the stars,
that tremble with love and with hope.
But my secret is hidden within me,
my name no one shall know…
No!…No!…
On your mouth, I will tell it when the light shines.
And my kiss will dissolve the silence that makes you mine!…
(No one will know his name and we must, alas, die.)
Vanish, o night!
Set, stars! Set, stars!
At dawn, I will win! I will win! I will win!