A prism is the solid shape you get if you move a flat polygon through space. A prism has five planes: a top, a bottom, and three sides. The most common kind of prism is a triangular prism, made by moving a triangle through space.
To figure out the surface area of a prism, calculate the surface area of each side and add them together. On a triangular prism, three of the sides are rectangles, and two of them are triangles. At least two of the rectangles are congruent (the same size), and the two triangles are also congruent.
To figure out the volume of a prism, think of the prism as a rectanglar solid sliced in half. So you multiply the length by the height by the thickness, and then divide the result in half.
One useful thing that is in the shape of a prism is a camping tent. Why might you need to know the volume of a tent? The attic of a house might also be in the shape of a triangular prism.
To find out more about geometry, check out these books from Amazon or from your library: