In 2018, the Farm Bill was passed which removed hemp derived CBD from the controlled substance list. So long as the product contains less than 0.3% THC, it is legal. These regulations vary from state to state, however, so it is important to research the legality of CBD in your state.
There is an immense amount of research being conducted on the health benefits of CBD. Studies are currently finding that some of the most common benefits appear to include relief and reduction in chronic pain, anxiety, stress, insomnia, and inflammation, as well as wound healing, just to name a few. Ongoing studies and regulations are required before making absolute claims.