An advanced learner needs to be good at describing his or her language skills. This is done with tables or key words in CVs or resumés, at times. But you need to gather Useful Language for whole-sentence descriptions.
A good tip is that you get acquainted with the different ways we have to do this depending on where we live or want to live. In Europe, we have a systema called the Common European Framework (CEF), with A2 (Elementary ad pre-intermediate), B1 (Intermediate), B2 (Upper Intermediate) and C1 (Advanced). But when you look for resources, notice how this is not the usual wording in other countries.
Share your resources here or in class.
I’m sharing this one, for countries in the CEF system: https://www.jobline.uni-muenchen.de/app_language/describing_language_skills/index.html