og:title
, og:type
, og:url
and og:site_name
are values from the Open Graph protocol.
If they are not hardcoded in your theme, they are probably coming from a plugin (look for "Facebook", "Share" or "SEO" plugins).
However: Using these name
values is not invalid! They are registered at MetaExtensions in the WHATWG wiki, which makes them valid according to the HTML5 spec. The validator is probably not up to date.