What does it mean to say that a shape has an area of 8 square inches?

It means that a shape consists of 8 squares that are 1 inch by 1 inch that make up the area of the shape. Imagine a side of a rubics cube. If we looked at the area we would say it is 3 by 3 and we would multiply 3x3=9. If you look at the rubics cube you would see the 9 squares on the one side.