This is the 8461st most frequent Russian word.
наша
"Нашa" means "our" (feminine form).
The word 'наша' is used here as a possessive pronoun indicating ownership or relation to the subject 'семья' (family).
Это наша семья.
This is our family.
Here, 'наша' is used independently as a pronoun to denote possession, referring to the implied subject 'книга' (book).
Книга — наша.
The book is ours.
In this sentence, 'наша' again serves as a possessive pronoun modifying 'школа' (school), showing possession or association.