Acrylic refers to a variety materials -- polymers or chemical compounds which are generally transparent forms of plastic. It's used in fabrics, paints and sheets of clear plastic.
Acrylic can be used for furnishings such as napkin holders, soap dishes, waste baskets, sculptures, paper weights, ornaments, makeup and drawer organizers, food storage and serving containers, dish ware and more. it can also be used to make furniture, although that's less common. It is useful for things like aquariums where the material should be clear. Generally it is less heavy than glass, and although it will crack, it's less likely to break or shatter than most glass.