The content quality tab covers:
Grade level: Flesch-Kincaid readability score. Flesch-Kincaid is a well-established metric of how hard content is to read.
Broken links: Links that don't work and return an error message. (Sometimes, links to login pages get marked broken. If you let us know about this, we can flag them so they don’t “count.”)
The "Current average grade level" displays a chart that allows you to visually compare the organizations in your filter. A lower grade level will mean your content is easier to read.
The "Current total broken links" chart shows the number of current broken links by organization.
Each organization you choose in your organization filter adds another bar to the bar charts for “Current average grade level” and “Current total broken links.”
Filtering by URL, page ID, or content type further filters down the data by just the pages you specify.
If you scroll down within the content quality tab, you can also see a table of broken links and grade level by page URL.