It means "(you) are".
Siete svegli in Italian is "You're awake" in English.
"Are you twins?" in English is Siete gemelli? in Italian.
siete impressionante
ragazze siete bei
Siete i migliori sorella
voi siete matti
"You are funny!" in English is Sei divertente! to one person, and Siete divertenti! to two or more individuals, in Italian.
"We missed you in church today" in English is Ci siete mancati in chiesa oggi in Italian.
"You all" is an English equivalent of the Italian word voi. The second person informal plural pronoun in question may be found employed in local or regional Italian as an admiring, respectful form for the singular "you." The pronunciation will be "voy" in Italian.
sei (one) siete( more) un dono di Dio
Siete una Bella Donna, I don't know how to pronouce it though.
"You are beautiful too!" in English means Anche tu sei bello! to a man, Anche tu sei bella! to a woman, Anche voi siete belli! to men and Anche voi siete belle! to women in Italian.