You learn how to interact with patients. You build your confidence, and learn what questions to ask. You learn about disease processes, and what to look for. You learn about surgical proceedures, and short/long term effects on the patient. You learn what answers to look for, and what answers you need to take action on. You learn your full body assessments, and you actually perform them. You begin to listen to chest sounds and bowel sounds, and learn the proper words to use to describe them. You learn how to actually do a dressing, empty a drain, and clean a REAL patient up. Eventually you learn how to balance patients; you'll probably start with one then work up to three (maybe even four) in your final clinical. You learn organization. How to plan your day to perform several bedbaths, assessments, diaper changes, feedings, IV meds, PO med passes, tests, etc. You learn how to be an expect diaper changer (depending on the type of floor you are on). You learn about medications, common medications, how they work, important things to check before giving, side effects, and interactions. You learn how to draw up and hang IV meds.
Finally, you learn whether or not you want to start out on medsurg, like everyone used to say was required for new nurses.