noun
general post office
Refers to the main or central post office in a city or region, handling major postal operations.
郵便本局は駅の近くにあります。
The general post office is near the station.
郵便局 is a general post office (any branch), while 郵便本局 specifically refers to the main or central post office.
Compound of 郵便 (postal service) + 本局 (main office).