Adding Structured Data markup (aka Schema Markup) to your eCommerce website helps search engines understand the product information listed on your site.
When search engines like Google understand the content on your site, they can then surface your Product Listing Pages (PLPs) and Product Detail Pages (PDPs) as a rich result, which showcases additional information like pricing, star ratings, shipping information and more.
The additional information can help customers make purchasing decisions and drive more traffic and sales to your site.