This is the 9534th most frequent Russian word.
федор
"Федор" is a Russian male given name, equivalent to "Theodore" in English.
The word "Фёдор" is used as a proper noun, referring to a person's name.
Фёдор работает в библиотеке.
Fyodor works at the library.
The word "Фёдора" is in the genitive case, as it is the direct object of the action in Russian explicit context.
Я попросил Фёдора помочь мне с книгами.
I asked Fyodor to help me with the books.
The word "Фёдор" is used in direct address, invoking the person's attention.