A view is a flat reproduction of a 3D-figure as seen from a certain direction. Most of the time three views are drawn: the front view, the side view from the right and the top view. Sometimes they are put into one figure called a three sided view.
In these view you often find line segments in a true scale. Hier you see the roof length in the top view and de roof width in the front view in a true scale, i.e. these length are not distorted.
You get the "net" of a 3D figure by folding it open at the edges, so that you get a 2D-figure. You could say that a "net" is a building plan in one piece without the edges.