"作实习医师" can be translated as "to work as an intern (doctor)" or "to serve as a medical intern" in English.
Here are a couple of example sentences to illustrate the usage:
* He is currently working as an intern (doctor) at a renowned hospital.
（他目前正在一家知名医院作实习医师。）
* During her medical studies, she served as a medical intern at a local clinic.
（在医学学习期间，她在当地一家诊所作实习医师。）