noun
two days; a period of two days
Used to express a duration of two days. Often appears with particles like 間 (for duration) or in time expressions.
二日間、東京に滞在しました。
I stayed in Tokyo for two days.
この仕事は二日間で終わらせます。
I will finish this work in two days.
二日 means 'the second day of the month' or 'two days' as a point in time, while 二日間 specifically emphasizes the duration of two days.
Compound of 二日 (futsuka, 'two days') and 間 (kan, 'interval, period').