The "Keep Private" is an internal admission field that someone from admissions would turn on when a candidate's application (and potential enrollment) needs to remain unknown. Two potential examples:
1. A celebrity is applying to your school, and they/their child needs their information kept private so it is not known.
2. Depending on a family situation or situation in general, a child might need to not even be publicly acknowledged as attending your school for their own well being.
This field has no functionality behind it and it will just function as a reminder/visual key for your admission team.