This is the 707th most frequent Finnish word.
uuden
"Uuden" means "of the new" in English.
Here, 'uuden' modifies 'vuoden', indicating possession and conveying 'New Year's' in English.
Uuden vuoden juhlat olivat upeita.
The New Year's celebrations were wonderful.
In this sentence, 'uuden' is the genitive form of 'uusi', modifying 'auton' to mean 'new car'.
Ostin uuden auton.
I bought a new car.
The word 'uuden' is the accusative case of 'uusi' (new), modifying the object 'auton' (car) and indicating that the car being referred to is new.