(동안)
동안 is a very useful word that can be used to indicate how long an action occurs. It is typically placed after a duration of time, for example:

2분 = 2 minutes
2분 동안 = for 2 minutes

10분 = 10 minutes
10분 동안 = for 10 minutes

이틀 = two days
이틀 동안 = for two days

동안 can also be used to indicate that an action occurs “while” another action occurs

저는 10분 동안 걸었어요 = I walked for 10 minutes
저는 30분 동안 공부했어요 = I studied for 30 minutes

While the translation of “동안” in these examples is usually “for”, in essence, what you are doing is stating “for that period of time.”

저는 10분 동안 걸었어요 = I walked for (a period of) 10 minutes
저는 30분 동안 공부했어요 = I studied for (a period of) 30 minutes
저는 이틀 동안 안 잤어요 = I didn’t sleep for two days