Creating Layout Viewport 创建布局视口

Layout viewports are objects that display views of model space
On each layout, you can create one or more layout viewports. 
Each layout viewport is like a closed circuit TV monitor of a view of the model at a scale and orientation that you specify.

Layout tab > Layout Viewports panel > Slant Arrow

Click New Viewports tab
Select Single
Click OK

Press [Enter] to fit

Viewport fit the printable area