Analytics
The numbers you may see about your published post.
When the site's owner has switched it on, a published submission shows an analytics panel: how many emails the post was sent in, how many were delivered and opened, how many clicks they received, and how many members the post signed up or converted. The numbers come from the site's own Ghost records and refresh every ten minutes.
Where the site has given the service the access this needs, the panel also shows where the post's new members came from, as a table of the sources that brought them with the free and paid members each brought, and the post's visitors where the site measures its web analytics. Otherwise it says that referrers are not available for the post, or that page views are not configured on the site.
If you see no panel, the owner has not switched it on.