This must be because you can't graduate as long as you fail one course. Whether you can graduate from college depends on how many credits you have. You can graduate as long as you have enough credits. You must pass every required course. If you fail the elective course, you can choose other subjects to take the exam again.

If a subject fails, there will be a make-up exam in the next semester, and it will be fine if the make-up exam is passed. If you still fail, there will be a total make-up exam in the last semester of the university, and it will be fine if you pass the exam then.

All universities are like this.

Nowadays, college exams are very simple, and generally there are not many subjects that fail. As long as you listen carefully in the last few classes and remember all the key points the teacher said, you can pass.