What is a student process?
My best guess: a student process is a process run by a student.

All users have to log in. The OS may well know various types of users, and may be able to determine from some table that a given user is a student. This can be useful to lower their priority for computer time in a shared machine used mainly for research, or possibly do the opposite during exam period. So having a scheduling queue for student processes would make sense.

As far as I know ... there is no direct relation to learning machines who would run processes that are studying something. But who knows? It may be coming.