In the context of search, structured data is a predefined schema that helps search engines better understand and classify the information provided on a web page, thereby making it more accessible to machines. It is also accepted as an SEO marketing technique to improve your traffic.
Structured data is a way to make your website speak the same language as search engines so they can easily understand what you're talking about.
To do this, you need a dictionary to translate your content into information that Google and other search engines can understand. The vocabulary used by the major search engines is Schema.org, which you can use to structure your website's metadata and help search engines understand your published content.
When a search engine understands the content of your web page, it can serve it to the relevant search queries, providing users with relevant and useful information for their search. Search engines can use structured data in so-called rich snippets to improve the user experience.