As Moz.com defines it, Schema.org (often called Schema) is a semantic vocabulary of tags (or microdata) that you can add to your HTML to improve the way search engines read and represent your page in SERPs.
The standard WooCommerce functionality already includes structured data mark up to display your product reviews effectively within organic search results. You don't need any additional plugins for this.
Our plugin extends the standard functionality and adds some extra mark up to help search engines properly crawl your shop (the standard WooCommerce functionality doesn't provide schema mark up for reviews with pictures).
It is important to understand that having a valid structured data mark up in place makes your website eligible for organic stars in Google but it doesn’t guarantee that they will be shown. You can test the rich snippets using Google’s Structured Data Testing Tool.