The Department of State has published the names of individuals added to the Department of Treasury's List of Specially Designated Nationals and Blocked Persons. This action is a result of these individuals meeting specific legal criteria under an Executive Order concerning harmful activities by the Russian government. As a consequence, their property and interests within U.S. jurisdiction are blocked, and U.S. citizens are generally prohibited from conducting transactions with them. Additionally, several Russian vessels, including research and drilling ships, have been identified as having interests tied to these individuals and organizations.
Simple Explanation
The U.S. Department of State has decided that some people and ships from Russia are doing bad things, so they can't do business with Americans or use their stuff in the U.S. anymore.