counter for months
日本に来てもう三ヶ月が経った。
Three months have already passed since I came to Japan.
この仕事は完成まで六ヶ月かかる予定だ。
This work is expected to take six months to complete.
一ヶ月の赤ちゃんを連れて散歩に出た。
I went for a walk with my one-month-old baby.