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.

Where is the diagram?

You need to include the original coordinates of the triangle to answer this. and how much does it translate (move left right up down)