Dashes and lines

Several lines of dashes are appearing at the bottom of some of my pages.
Where do they come from? I’m unable to delete them.

Thank you.

You are probably in Scrivenings view and have selected something in the Binder which contains sub-documents without text.

Could you please elaborate.
These dashes appear at the bottom of a page (or pages) text.
What exactly would cause this and why can’t I delete them?

Have you done the interactive built-in tutorial?