The Secretary of State has imposed sanctions on six individuals in accordance with the President's Executive Order on Hong Kong Normalization. These individuals are accused of being leaders in implementing the National Security Law, engaging in activities such as arresting and detaining individuals. As a result, these individuals have been added to the list of Specially Designated Nationals and Blocked Persons, meaning their assets in the U.S. are blocked and U.S. persons are prohibited from dealing with them. The decision took effect on January 15, 2021.
Simple Explanation
The Secretary of State decided to freeze the money and stop Americans from working with six people who were helping make a new law in Hong Kong, because that law could be bad for some people.