This is the 92nd most frequent Lithuanian word.
viena
"Viena" in English means "one" or "alone."
In this sentence, "viena" is a numeral, specifying one single book.
Aš nusipirkau viena knygą.
I bought one book.
Here, "viena" means "alone", used to describe someone's state.
Ji yra viena namuose.
She is alone at home.
In this case, "viena" is used to emphasize a single specific song out of a group.