1.
twenty days
A period of twenty days.
二十日かかった。
It took twenty days.
二十日ぐらいかかる。
It takes about twenty days.
二十日間休みを取った。
I took twenty days off.
工事は二十日で終わる予定です。
The construction is scheduled to be completed in twenty days.
薬を二十日分もらったので、来月まで足りるはずだ。
I received twenty days' worth of medicine, so it should last until next month.
2.
twentieth day of the month
The twentieth day of any month.
一月二十日
January 20th.
二十日に届きます。
It will arrive on the 20th.
二十日までにお届けします。
We will deliver it by the 20th.
来月の二十日に会議がある。
There is a meeting on the 20th of next month.
二十日は祝日なので、学校も会社も休みです。
The 20th is a holiday, so both school and work are off.
二十日 is a special reading.
SPECIAL DAY READINGS:
- 一日 (1st)
- 十日 (10th)
- 二十日 (20th)
- 二十四日 (24th - regular + special)
NOTE: After 10, most days use regular Sino-Japanese numbers + 日, but 14th, 20th, and 24th have special readings.