Event/Time + 期间 + Clause
期间 (qījiān) is a noun meaning "period," "duration," or "during." It refers to a span of time within which events occur. It typically follows a time expression or event noun to specify when something takes place, functioning similarly to "during" in English.
考试期间请不要使用手机。
Kǎoshì qījiān qǐng bú yào shǐyòng shǒujī.
Please do not use your phone during the exam.
暑假期间我打算去旅行。
Shǔjià qījiān wǒ dǎsuàn qù lǚxíng.
I plan to travel during summer vacation.
她在北京工作期间学会了说普通话。
Tā zài Běijīng gōngzuò qījiān xuéhuì le shuō pǔtōnghuà.
She learned to speak Mandarin while working in Beijing.