Actions operate either on a single page or on the whole Wiki.
AttachFile: Attach files to a page (HelpOnActions/AttachFile)
DeletePage: Delete a page (after a security question)
LikePages: Lists pages with similar title
LocalSiteMap: List of all pages that are referred to, up to a maximum of 4 levels
SpellCheck: Call check spelling for the current page (HelpOnSpellCheck)
For details see HelpOnActions.