This is the 57th most frequent Serbian word.
први
"Први" means "first" in English.
Here, 'први' (prvi) is used as an ordinal adjective meaning 'first', describing the noun 'час' (class).
Ова је мој први час српског језика.
This is my first Serbian language class.
In this context, 'први' signifies the ordinal position of a task (first) and modifies the noun 'задатак' (task).
Мој први задатак је да научим основе.
My first task is to learn the basics.
Here, 'први' forms the phrase 'први пут' (prvi put), meaning 'for the first time' in this fixed expression.