It is curd made from soy beans. As for what is used for? Well hundreds of thousands of uses. I personnaly use it to threaten my kids with if they are bad.
it's very nice in a stir fry, but needs heaps of help as it has the texture and taste of a wet sponge! Plenty of ginger and soy sauce and garlic! You can make it into a vegan friendly cream by pureeing it in a blender. It is indeed very versatile.