The Meta Twitter Report
The meta twitter report reports on twitter meta tags on pages, these are generally only used to determine how links to your pages show on twitter - although some other sites may use them.

Source URL
The page the twitter tags are found on.
twitter:card
The twitter card type. Often it makes most sense for this to be 'summary_large'
twitter:title
The twitter title
twitter:description
The twitter description
twitter:image
The image to display on any card
twitter:image:alt
The alt text for the image
twitter:url
The url of this page (generally the same as "Source URL")
twitter:site
The site name
twitter:creator
Creator details