This is the 344th most frequent Chinese word.
期间
"期间" means "period of time" or "during."
Here, '期间' is used to specify a time frame within which the action of traveling to Beijing occurred.
暑假期间，我去了北京旅行。
During the summer vacation, I traveled to Beijing.
In this sentence, '期间' refers to the period of the medical treatment, emphasizing the ongoing nature of the time frame.
在治疗期间，他坚持每天锻炼身体。
During the treatment period, he insisted on exercising every day.
'期间' here refers to the duration of the meeting, during which the request for silence applies.