This is the 7488th most frequent Russian word.
демуров
The word "демуров" does not appear to have a meaning in Russian; it might be a proper noun, surname, or misspelling.
In this sentence, 'Демуров' is used as a proper noun, likely someone's last name. Proper names are capitalized and are not directly translated into another language.
Демуров всегда был честным человеком.
Demurov has always been an honest person.
Here, 'Демуровом' is the instrumental case of 'Демуров', indicating the person proposing the ideas. In Russian, cases modify nouns to fit their grammatical role in the sentence.
Мы обсуждали идеи, предложенные Демуровым.
We were discussing the ideas proposed by Demurov.
In this usage, 'Демурова' is in the genitive case, referring to possession — the book belonging to Demurov. This shows how nouns change forms depending on their function in a sentence.