What does this report contain?
Pages that can't be indexed by search engines because they contain a robots noindex directive in the robots meta tag, robots.txt file or X-Robots-Tag in the header.
How can this report be used?
These pages can be crawled but not indexed, so the only value to search engines is if they can be used to discover new pages. The noindex directive is typically applied to low value pages that don't offer any unique SEO value but that link to pages that do offer SEO value, which would not be discoverable otherwise.