A section view is a view that shows the internal parts of 3D bodies in a design. It looks as if you cut through an entire length of the design. You can use this view to look at and modify the internal parts of your model.
Select 
in the title bar to enable section view. 
You can select
to turn off the section view.
You can also select a plane or face and then 
to see the section view along the plane or face.