If by “the wrong class” you mean a level that is too high or too low for you in math or foreign languages, it’s not a problem because those departments allow you to move back and forth to a course at the appropriate level that fits into your schedule. If instead you mean a class that you start attending and decide you really don’t like, you have seven class days to drop the course and add another. After that, your schedule is set. Twice during your fours years you may withdraw from a class before the end of the tenth week of classes. In such cases a W appears on your transcript to show you were registered for the course and were a full-time student. Talk to your advisor about the process.
It’s important to remember that the course number is a general guide to which students the course is appropriate for. In general, 100 and 200 level courses are introductory courses and are appropriate for first-year students. By contrast, 300 and 400 level courses tend to be designed for majors or for students with prior experience in that area of study. Some might be available and appropriate for first year students, but you should definitely talk to your advisor about any that look of interest.