The only country in the world today with a pure command economy is North Korea. Even that country has some amount of a black market that is not controlled by the government, but the government is much more in control of its economy than any other government in the world.
In a pure command economy, the government makes all of the economic decisions. The government decides what products are to be made. It decides how they will be made. It decides who will get to use the products. The government owns all of the “means of production,” that is, the government owns all the factories and other places of work. There are no private companies and people do not have economic freedom.
Every country in the world has some aspects of a command economy. In the US, for example, the government provides public schools instead of leaving schooling to the private sector. However, market forces are much more powerful than the government in most countries’ economies. Even China, which has an authoritarian government and is officially communist, has many private companies and allows most of its state-owned companies to run on market principles. The countries in the world today whose economies are closest to being pure command economies are probably North Korea, Belarus, and Cuba.