Cacao nibs are pieces of cocoa bean. They are basically like cocoa powder, but not powdered.
These cacao nibs are raw. Raw cacao beans are hard to come by, because they are usually roasted. Cacao is actually quite a nutritious plant, being high in antioxidants and minerals. Research has shown that cocoa can induce feelings of well-being (which is pretty obvious really). Raw cacao is the purest form of cocoa - no sugar, and not even roasted (as most cocoa powder is).
These cacao nibs are still crunchy, but they are not roasted, and so retain more of the flavour and nutrients.