A post office — a public facility that handles mail, sells postage, and offers various postal services.
郵便局で小包を出してきた。
I dropped off a parcel at the post office.
年賀状は郵便局で買った切手を貼って出す予定だ。
I plan to put stamps bought at the post office on my New Year's cards and mail them.
近くの郵便局は土曜日も窓口を開けている。
The nearby post office also has its counter open on Saturdays.