Structured data is any data that is organized.
Structured data markup, also known as schema markup, is code that you add to your website to help search engines produce more detailed and informative results for search engine users.
Structured data markup tells the search engine what the content actually means.
Using structured data correctly can help search engines better understand your content and might act as a stronger indicator of relevance in the eyes of a search engine. However, the use of structured data markup is not a direct ranking factor.