Posted by Review rich results is a type of schema that can be coded onto website pages to display a star rating on your SERP listing.
Because social proof is an important aspect in the discovery and consideration stage of the buyer’s journey, having this review schema can be helpful in validating your product or service for prospects right from the start. It can also help differentiate your listing from others on the search results page.
https://webmasters.googleblog.com/2019/09/making-review-rich-results-more-helpful.html