This is the 609th most frequent Croatian word.
prvoj
"Prvoj" is the dative or locative singular form of "prva," meaning "first" (feminine) in English.
Here, "prvoj" functions as an adjective describing "stranici" (page), indicating its ordinal relationship - the first in a series.
Na prvoj stranici knjige je napisano ime autora.
On the first page of the book, the author's name is written.
In this example, "prvoj" describes "smjeni" (shift), indicating it is the first of multiple shifts.
U prvoj smjeni radim cijeli tjedan.
I am working in the first shift the entire week.
Here, "prvoj" modifies "razini" (level), signifying its positioning as the first step in a systematic course structure.