On the posted book page it has a column called action.  What is this refering to?

Hi John,

The Actions refer to the things you can do with the books in your Bookshelf: Post, Hold or Delete.

If you choose Post then it will post a book you select that's on hold. If you choose 'hold' it will put on hold any book you select that it's posted. If you choose 'delete', then it will delete any book you select.