Study the questions and answers at the end of each chapter in the ASA Basic Keelboat book, you'll be okay. Even though your lessons are by day, pay attention to the running
lights, several questions on this. Also capacity plate, what not to throw overboard, when/how to report accidents, what are the 5 top things making a sail dangerous (like
fuel leak, insufficient PFDs/fire extinguishers, overloaded, etc.), buoyage, basic rules of the road, stuff like that. It's all in the book and chapter reviews at the end. This is good stuff to read up on in advance
On the practical how-to-sail side, you'll want to show you can tack, jibe, hold course, get sails trimmed right, and get from and to your dock under reasonable control, know how to do a crew overboard recovery (life cushion used, much lighter to get back on board, ha ha), know the basic parts of a boat, how to
anchor, how to reef (not on test, but you should learn it), get out of irons, general stuff. You learn this stuff by doing much more so than reading about it, ask questions (lots of them) and "it'll come to you" as you sail. Then read after each lesson, the book makes much more sense once you've sailed a little rather than vice-versa.
You'll be fine.