This is the 252nd most frequent Croatian word.
prvu
"Prvu" means "first" (feminine singular accusative) in English.
The word 'prvu' is an accusative feminine singular form of the adjective 'prvi', meaning 'first', agreeing with 'knjigu', which is a feminine noun in the accusative case.
Prvu knjigu koju sam pročitao bila je vrlo inspirativna.
The first book I read was very inspiring.
Here, 'prvu' modifies 'osobu', which is a feminine noun in the accusative case, and 'prvu' agrees in gender, case, and number.
Prvu osobu koju sam sreo na zabavi već od ranije poznajem.
The first person I met at the party I already knew from before.
The usage of 'prvu' in this sentence corresponds to the feminine accusative singular form, modifying 'lekciju', aligning in grammatical agreement.