This is the 145th most frequent Serbian word.
прва
"Прва" means "first" in English.
Here, 'прва' is used as an ordinal number meaning 'first,' describing the position of the house on the street.
Прва кућа на улици је моја.
The first house on the street is mine.
In this sentence, 'прва' is again ordinal but refers to a person being the first to perform an action (arriving).
Она је прва која је стигла.
She is the first one who arrived.
Here, 'прва' denotes the sequential position of a creation among others, indicating that it's the first work the speaker composed.