This is the 4273rd most frequent Russian word.
администрацией
The Russian word "администрацией" means "by the administration" or "with the administration" (instrumental case of "администрация").
The word 'администрацией' is used in its instrumental case form, indicating the institution (administration) with which an agreement was made.
Мы согласовали план с администрацией компании.
We agreed on the plan with the company's administration.
Here, 'администрацией' is used in the instrumental case to show the entity performing the action (approval).
Проект был одобрен администрацией города.
The project was approved by the city's administration.
In this sentence, 'администрацией' denotes the entity consulted for the resolution of the issue, again in the instrumental case.