What kind of economic system does a socialist country have?

There are diverse kinds of socialism. A purely socialist country would have an economic system based on collective ownership of resources, production, land, etc., by the workers. Communist countries usually have economic systems where the government owns all the means of production. In traditional communist systems, there is no private property or enterprise. In recent decades, Chinese capitalism has evolved to include private property and capitalism. Others form of socialism such as social democracy, which exists in Scandinavian countries, allows for mixed economies. In Sweden, Denmark, Norway, and other social democratic countries, there exists both government ownership of the means of production, as well as a vibrant private sector. Most modern societies, including the US, include elements of socialism.