This is the 9162nd most frequent Russian word.
сергеем
"Сергеем" is the instrumental case of "Сергей," a male given name, meaning "with Sergey."
'Сергеем' is instrumental case, identifying the individual participating in the discussion.
Мы обсуждали проект с Сергеем.
We discussed the project with Sergey.
The word 'Сергеем' is in instrumental case, showing with whom the action is performed.
Я готовлю обед вместе с Сергеем.
I am preparing lunch together with Sergey.
Here 'Сергеем' is in instrumental case, indicating the person who is involved in the sharing action.