Projections are used in an engineering drawing to show a particular view. Most drawings use orthographic projections set at 90 degree angles (FRONT, TOP, LEFT etc). A common pictorial projection is isometric
Orthographic and IsometricOrthographic and Isometric: (Notes)
Australian standard projection is 3rd angle. You draw what you see from that side. E.g. The right view shows what you would see if you stood on the right side. First angle is the opposite to 3rd angle - like rolling the object on the paper and drawing what you see looking down.
Third Angle Projection (below). The view is displayed on same side as it is seen from.
First Angle Projection (below). The view is displayed on opposite side as it is seen from. An alternative way to understand it: Roll the object on the paper, then draw the view as you see it.
Example of First or Third Angle Projections (below):
Section views are used to show details inside an object. (or an assembly)