They’re a market based mixed economy. Mixed means both socialist and capitalist (public and private ownership of the means of production).

It’s Communist in the sense that there’s only one political party, the communist party. And their goal is to move towards socialism.

The Đổi Mới economic reforms were initiated by the Communist Party of Vietnam in 1986 during the party’s 6th National Congress. These reforms introduced a greater role for market forces for the coordination of economic activity between enterprises and government agencies, and allowed for private ownership of small enterprises and the creation of a stock exchange for both state and non-state enterprises

The economic reforms aimed to restructure the Vietnamese economy away from Soviet-type central planning and towards a market-based mixed economy intended to be a transitional phase in the development of a socialist economy. The goal of this economic system is to improve the productive forces of the economy, developing a firm technical-material base for the foundation of socialism, and to enable Vietnam to better integrate with the world economy.