A Blocked Account (“Sperrkonto” in German), works as a proof of financial resources for people that are planning to apply for a visa/residence permit for their stay in Germany. The main groups of people that are required to have a Blocked Account are students, au pairs, language students, job seekers and basically everyone whose stay in Germany is not supported by some external sources such as salary, scholarship, etc.
The money transferred to the Blocked Account is initially “frozen” until the account holder arrives in Germany. Afterward, he/she starts receiving a set amount of money every month. Since September 1, 2019, the German Federal Foreign Office requires the applicants for visa to deposit, €853 per month of planned stay in Germany, which makes it €10,236 per year.
Note: the Blocked Amount requirements of local embassies might differ from the general requirement, therefore, it is important to consult with the embassy you are planning to apply with, to ensure that you satisfy the local criteria.