This is the 813th most frequent Russian word.
отделения
"Отделения" - divisions, branches, departments, or compartments, depending on context.
Here, 'отделение' refers to an 'office' or 'branch' of a larger organization, specifically a post office branch.
Мы посещаем почтовое отделение, чтобы отправить письмо.
We visit the post office to send a letter.
In this usage, 'отделение' refers to the 'separation' or 'division' of materials.
Эта зона была оборудована для отделения мусора.
This area was equipped for garbage separation.
Here, 'отделение' again refers to an 'office' or 'branch,' in this case, of a bank.