This is the 959th most frequent Finnish word.
jari
"Jari" is a common Finnish male given name.
In this sentence, 'Jari' is a proper noun used as a personal name.
Jari on ystäväni.
Jari is my friend.
Here, 'Jari' is again a personal name, identifying a specific person and their occupation.
Jari työskentelee opettajana.
Jari works as a teacher.
In this sentence, 'Jarin' is the genitive form of the proper noun 'Jari', indicating possession.