To go into more detail, here's the typical lecture format at a German university (note that this is "typical", not universal, and professors have a lot of leeway in how they can structure their courses).
There'll be a lecture twice a week (four "semester hours", 2 times 2 * 45 minutes) and a two semester hour exercise session. The lecture will be held by a professor [1]; the exercise session for undergraduate courses will generally be conducted by a TA in smaller groups.
More often than not there won't be a textbook, except for heavily standardized courses (or where the professor chooses to pick one). You'll work off the professor's lecture notes and any notes that you took yourself (sometimes the lecture notes are basically a textbook by themselves, but that's obviously a lot of work for a professor). The lecture notes may recommend additional literature, which is generally available through the library's course reserves (and out of which students will photocopy anything they consider relevant; private copies short of wholesale copies of books are generally legal in Germany) or online (in the case of individual papers).
You'll get homework once a week, distributed as printouts during the lecture (and/or available on the course website). Students are encouraged to work on homework in groups and to even turn in their results as a group.
Homework will be graded, but it doesn't count towards your final grade; instead, you will be required to get 50% of the total points to be admitted to the final exam (this is more an incentive than an actual threshold). You can generally even copy the results from somewhere else (you're doing homework as preparation for the exam, so you're only hurting yourself if you do it).
Homework will be returned and reviewed during the exercise session, usually with either the TA or one of the students presenting the solution to each question on the blackboard and discussing it.
Your entire grade will be derived from the final exam (some courses these days have two exams, one midterm and one final exam so that your entire grade doesn't ride on one day's performance). Some courses may also have an oral rather than a written exam.
There generally won't be grading on a curve (though the professor can adjust the grades if the exam turned out to be harder than intended). If you fail to meet the standards that the university expects of its students, you fail. German professors won't shy away from letting most of the students in a course fail (though they will likely be sad when that happens). That's the price of a mostly open admission system combined with the university's desire to maintain its academic reputation.
In addition to lectures, there will be (depending on the subject), seminars, lab courses, etc. You will also have to write a thesis (including for a Bachelor's degree).
In general, there's very little handholding (that's not specific to Germany, though). You're expected to be able to both study independently and work productively in a group (skills that you should have learned in school) without needing support.
[1] Using the term "professor" broadly to include "privatdozenten" etc.