This is the 37th most frequent Italian word.
sia
The Italian word "sia" means "both" or "whether," and it is also used as a subjunctive form of the verb "essere" (to be).
Used as a conjunction to list two elements.
Sia il fratello che la sorella amano la musica.
Both the brother and the sister love music.
Used as the third-person singular subjunctive form of 'essere'.
Spero che sia felice del suo successo.
I hope he/she is happy with his/her success.
Used in paired conjunctions to indicate alternatives or instances.