This option controls whether pages within the PDF document should be orientated to have primarily horizontal text, even if the page was rotated in the PDF.
The option is intended to allow landscape oriented pages within a Word document to be reconstructed with landscape orientation, even if they were rotated to allow printing.
In the following example, the second page is a diagram with a title. It has been rotated so that although the page has a landscape orientation, it fits in with the rest of the protrait-oriented document.