This is the 452nd most frequent Latvian word.
jauna
"Jauna" in English means "new" or "young" (feminine form).
In this sentence, 'jauna' is used as a predicate adjective agreeing with the subject 'Viņa' (She), meaning 'young'.
Viņa ir ļoti jauna pēc izskata.
She looks very young.
Here, 'jaunu' is the accusative singular form of 'jauns' used as an adjective to describe the noun 'grāmatu' (book), meaning 'new'.
Es nopirku jaunu grāmatu.
I bought a new book.
Here, 'jauna' is also a predicate adjective agreeing with 'māja' (house), indicating its renovated, fresh state.