Google uses rich snippets as a way to enhance the listing in their indexes. This plugin makes a user defined and controlled dataset availble to Google. So that when the search engine scans your website you can define what data it sees.
This Add-on allows you to control the page title, description, and even the image that Google will see, to make it more versitile the add-on allows you to set defaults to make sure that there is always data to list. The defaults are set in the admin control panel, you can set the default page Title, the page Description, and the default image to use.
On any page these values can be overridden with different values by adding attributes to the page.
There is an 'Order of precedence' Applies to the Image, Title and Description
For these elements there is an order that the value is selected. If you have set a page level attribute that is used, otherwise the page value is used, otherwise the meta value is used, finally the site wide default is used.
This Add-on is defined as Beginner because it is extremely easy to get started. But also gives you the flexibility to define exactly what you want Facebook to see.