Be Prepared For Public Speaking!
If you sign up for a language course, seminar, or full module at a German university you'd better be prepared for some public speaking to be part of your studies, and I'm not just talking about discussing the topic at hand amongst yourselves in your grammar class.
A typical university module will include in some number lecture (Vorlesung) and seminar components. For the seminar, you will be expected to either write an essay or give a presentation (Referat, if you are in a German language course). Regardless of the type of course you are in, be it a language course, history course, or biology course, you will likely be required to give a presentation on a topic, or in the case of the sciences, a journal article that you are assigned to.
Depending on the responsible professor or lecturer, the presentation time will usually range from 10-20 minutes, with time after for questions from both your classmates and themselves. While the obvious best practices for giving a presentation apply, like staying in your allotted time(!), practicing in advance(!!), and being clear on your topic(!!!), remember that your grade is also substantially influenced by your ability to answer questions on your presentation. It's also worth bearing in mind that it's not uncommon for these presentations to be expected to teach the particular concept or topic you have been assigned (in seminars, not in language courses).
The good news about giving presentations for seminars is that you typically don't need to take an additional exam on the same topic, and depending on the subject, the seminar presentations themselves may not be on your lecture's final exam. You should make a point of clearing up what you will and won't be responsible for with regards to the actual exam at the end of the semester, in order to spare any last minute surprises about your final though. If you aren't taking the actual lecture, and are just taking the seminar as part of your studies, make sure that you get a certificate for your credit from the seminar issued to you at the end of the semester. It's not the norm to take just a seminar without taking the lecture that completes the module, so you'll have to make sure to get the certificate, as it outside of the typical operating procedures.