All of your pages contain information structured in a visual way so that human visitors can understand it. Think of a product page- these are laid-out in such a way that a visitor can see what the product is, how much it costs and how buyers rate it.
This information is not always obvious to a search engine. Separating out a product description, name, price, images etc. can be tricky. Structured Data is a way to include a version of this information in the page to tell a search engine precisely what each piece of data is.
Just like HTML is a standard, there's a standard for Structured Data. Plug in SEO Plus includes structured data on all relevant pages in your shop without any extra work for you. This unlocks some pretty interesting things to improve your SEO...
Logo, Social Profile Links
The good news is that once you've completed the initial setup Plug in SEO Plus automatically generates Structured Data for you wherever it is appropriate on your shop.
It isn't showing up in search results
Like any information from your site it is at the discretion of a search engine if they show it or not. Typically your site should already appear well in search results in a 'plain' format before being considered for structured data enhancement.
Wait a few weeks after adding Plug in SEO Plus, make sure you've updated your shop with some fresh content and then use Plug in SEO, Google Search Console, Bing Webmaster Tools to check there's nothing else hindering your search engine performance.