noun
self-study time; study period
Refers to a designated period for independent study, often in a school setting.
今日の自習時間は図書館で過ごした。
I spent today's self-study time in the library.
自習時間に何を勉強すればいいですか。
What should I study during self-study time?
自習 is the act of self-study, while 自習時間 specifically refers to the time period allocated for it.
Compound of 自習 (self-study) and 時間 (time).