This is the 9933rd most frequent German word.
oleg
The word "Oleg" is not a German word; it is a Slavic male first name.
Here, 'Oleg' is used as a proper noun representing a person's name.
Oleg ist ein russischer Name.
Oleg is a Russian name.
In this sentence, 'Oleg' is used as a direct object signifying the person met by the speaker.
Ich habe gestern Oleg im Park getroffen.
I met Oleg in the park yesterday.
Here, 'Oleg' is used in genitive case to denote possession of the stories.