The Offsite Links Report
The offsite links report is the opposite of the internal links report. It shows all links that are leaving a site.

Source URL
This is the page that the offsite link is originating from. It's the page where you would want to look for it.
Outbound Link
This is the target url of the link - or in other words the url of the offsite page.
Anchor
This is the anchor used in the link. An idea is to try using the "Filter text..." box to find keywords that may often be in these links.
Site Relevance
The theme similarity between the page being linked and the crawled site. 1 means they are the same.
Page Relevance
The theme similarity between the page being linked and the page linking to it. 1 means they are the same.