When you tick this option (the default), the "entries" and "text" type fields are printed with the box around them (like you see them on the window). This is useful for printing plain windows.
If you don't tick this option, only the contents of the "entry" and "text" type fields are printed. This may be useful for printing "Form" type windows where there is a background image as a form.
Since this is a global setup, all your windows will take this option unless overrode locally.
See the examples Entries and Text.