I assume it means in a roleplay sense. Most RP servers I've been in only have prerequisites for higher positions (e.g. teachers/police), so I personally didn't expect many, but I can see why you'd want being a student to be more meaningful. At the very least, I think reading and accepting the campus rules should be one of them. I was once in a server that had a quiz for all users that checked they understood the basics of RP (knowing what universe you're RP'ing in, understanding godmodding, grammar check, etc), so you could have people complete that to become a member as well, but it could be seen as too serious/harsh.
As for what it means to be a student, I guess it means you're someone who is interested in learning new skills, self-development, helping each other and building friendships together as a community?