This is the 759th most frequent Croatian word.
novoj
"Novoj" is the dative or locative singular form of the adjective "nov" in Croatian, meaning "new" in English.
In this sentence, 'novoj' is the dative case of the adjective 'novi', agreeing with 'godini' ('year'), which is the object of the preposition.
Radujem se novoj godini.
I am looking forward to the new year.
Here 'novoj' is the locative case of the adjective 'novi' (meaning 'new') agreeing in gender and number with 'zgradi' ('building').
Idem u školu u novoj zgradi.
I am going to the school in the new building.
Here, 'novoj' is the locative case describing 'proslavi' ('celebration') as the location or context of the preposition.