The new President has ordered a federal civilian hiring freeze. Ne vacancies may be filled. No new positions may be created. There is an exception for Senior Executive Service positions. The Director of the Office of Management and Budget (OMB) can grant exceptions from the order.
This is in line with the long-standing Republican talking point that the "federal bureaucracy is bloated." A hiring freeze couldn't possibly cause a problem if there are way too many employees.
The reality is that federal agencies are already understaffed. A hiring freeze creates problems almost immediately and the problems get worse and worse as the hiring freeze goes on but to understand this you have to have some knowledge about how government works and some concern that it actually does work.