The Prime Minister is helped and advised by his or her Cabinet, which is a group of senior ministers, many of whom are in charge of departments like the Department of Health or the Department for Education.
Government departments are staffed by civil servants. Ministers decide on policy and civil servants are responsible for making this happen.
All ministers who work for a department are part of the Government.
The Government will sometimes be referred to as central government. It is not to be confused with local government.