Open Graph Tags
The Open Graph Tags are used for integration between Facebook and your site. The tags become rich "graph" objects with the same functionality as other Facebook objects. They can show extra information (name, description, image or price) in posts, pointing to your store. The Open Graph Tags are also recognized by Twitter, Google+ and LinkedIn.
In the image below you can see how the shared data can be customized by using the OG tags:
Twitter Cards is a variation of the above. They are made specifically for Twitter by displaying extra information on the tweets in the form of descriptive posts, pointing to your store.
The fields App ID (in Facebook settings) and Username (in Twitter settings) are optional.
Language Annotations, a.k.a. "hreflang" Tags
Many websites serve users from around the world with content translated or targeted to users in a certain language. Google uses the rel="alternate" hreflang="x" attributes to serve the correct language or regional URL in Search results page.
From the options on the left side, you can enable the "hreflang" tags for the product, categories, manufacturer and information pages.
NoteThis option is intended for stores with more than one language and it will work only if you have activated more than one language for your website.