Here you can set all of your social networks. They will appear in the footer (if you have enabled a social media block), and will also appear in blocks such as 'Instagram', as a link to your Instagram profile.
There are a few options in 'Social media' that can help increase interactions with your social profiles.
Enable product sharing shows a 'Like', 'Tweet' and '+1' box on all of your product pages. Enable blog post sharing does the same on all individual article pages.
Below you can set what sharing boxes are shown.