Dear Tangdi Luan,
There is no general "examination period" at Universität Hamburg.
When your exams take place depends on the specific degree program and the particular exam. In general, information about the exams is announced in the first session of the respective course or earlier in the description of the course in the course catalogue
. The course catalog for the winter semester 2021/22 is not yet available, but should be published soon.
The form of the exams ("online" or "face-to-face") in the winter semester 2021/22 varies depending on the degree program and the exam. As already mentioned, this information is usually given in the first session of the course. If this is not the case, you have to contact the lecturer concerned or the academic office
of the respective department for further information.