A mentor is supposed to help you with pretty much everything around the site if they can. The classes allow one on one help between a reviewer who wants to get help writing reviews and a mentor. It's not necessary to sign up with a class if you don't plan on reviewing but still have questions, you can just ask a mentor via message and most of us are more than happy to answer you back, even if you think the question is silly or stupid. All questions are worth being asked and being answered.

That's the basic gist of it, but you can always read through the student's guide to the mentor program as well.

As Sam said, mentors will answer questions, and help you with anything around the site. A large part of the mentor program is helping students to write better reviews. When you take a class, you can submit your reviews to your mentor before they are published. They will make suggestions on how you can improve, and make your reviews more useful to readers. The mentor program is also one of the ways that you can become an advanced reviewer. You will become advanced when you graduate from a class.

The mentor program is fantastic! (I say this as a current student). Basically, a class is just a one-on-one thing that connects you to a mentor, who is an advanced reviewer who really knows their way around EF and has written a lot of helpful reviews. After writing a review, instead of submitting directly to an editor, you submit it to your mentor. They'll read it and give you comments and suggestions about how to improve. You then edit your review, and submit it back to them for approval. In the meantime, you can ask them questions about what to include in reviews, how to improve your writing, and any questions you have about reviewing, features of the site, etc.