Many foreign matriculation examinations are recognised in Germany. In this case you can be admitted directly to a course of studies - provided that you have sufficient knowledge of German.
For students applying from certain other countries the matriculation examination from their homeland is not enough. For example, to be able to apply to study in Germany they must have already studied for two years in their home country, or they must take a so called assessment test. The admission rules for the assessment test also vary - sometimes the applicant must also have already studied for one year in his or her homeland.
If you have already completed your degree in your home country then as a rule you will be able to study in Germany. However, not every graduate with a bachelor qualification is admitted to a German master's course.
Points of contact for these questions are the students' offices at the universities.