This is the 7527th most frequent Japanese word.
典夫
"典夫" (Norio) is a Japanese male given name.
Here, 典夫 is used as a proper noun, referring to a person named 'Norio' in the sentence.
典夫さんは大学生です。
Mr. Norio is a university student.
In this sentence, 典夫 is again a proper noun functioning as the subject, and it is marked as the possessor of the hobby.
典夫の趣味は読書です。
Norio's hobby is reading.
Here, 典夫 is used to denote the person one is talking to, showcasing its role in relational context.