What does the minimum length of service 15 mean in the recruitment requirements? What does this mean?

You are required to have worked in this post or this hospital for at least 15 years before you are eligible to transfer or leave.

Reason: It takes some time for a hospital to train a doctor, that is, clinical experience. Go to this hospital after graduation, work for at least one year, and then set up a post in the department. For example, internal medicine, including cardiology, respiratory medicine, neurology ... you need a qualified old doctor to take you to work, and you will be sent out for further study after a certain period of time.

Therefore, the hospital is worried about training you to be a truly qualified doctor. If you leave your job halfway, the hospital will lose a lot.