Whether you need an entry visa for Germany or not depends on your country of origin. Please follow the link to check the requirements that apply to you.
If you need a student visa, please contact the German embassy in your home country in order to apply (find embassy near you).
Your visa will be valid for three months. Within this time frame, you have to convert your visa into a residence permit. Please note that a three months tourist visa cannot be converted into a residency permit for the purpose of studying.
It may take several months for a visa to be issued. Please make sure to check the visa processing times in your home country.
In any event, it is important to apply for a visa as soon as you have received your letter of admission from Brand University of Applied Sciences.