I took two art classes at my community college and I loved them! Drawing 1 and Figure Drawing. Obviously it depends on the college, class, and teacher, but I can tell you my experience.
In an introduction class like Drawing 1, no one's expected to know how to draw. Figure Drawing is different because Drawing 1 is a prerequisite, so you'll have more drawing experience for it. In both classes, our exercises were always drawing from life. In D1 it's drawing shapes and environments with an emphasis on the drawing elements (composition, line quality, proportions, etc.) In FD, it's drawing people and making gesture drawings with an emphasis on accuracy instead of style.
I'd suggest one thing to prepare yourself mentally: take the class as a learning experience and not as a chance to prove yourself. All the fun will be sapped out of it if you compare yourself to others or think that the teacher is only critiquing you because your art sucks (it's great if the teacher critiques you, actually, it shows they care). You're taking the class to improve and trust me, improve you shall. I wouldn't be where I am today artistically if I didn't take my drawing classes.
Good luck!