To "fixed period of time for work", it is "工作时间" (NOT "工时"), so, you can say: "你（们）的工作时间是怎样的？" or "请告诉我你们的工作时间？" also "你（们）的工作时间是几点到几点？" The latter sounds more colloquial. In addition, "你（们）的工作时间是什么时候？" This is not quite accurate words. "什么时候" means "what time". I think in such the sentence the "work hours" should not be construed as "工时" (man-hour).

上班時間幾點到幾點? 工時多長?

You can say "你（们）的工作时间是什么时候？"

你什么时间工作？

thank you so much!!!