Article schema tells machines the basic facts about a piece of content: its headline, description, image, author, publisher, the date it was published and the date it was last changed. Variants such as BlogPosting and NewsArticle exist for more specific cases, all defined in Schema.org and usually written as JSON-LD.
The values should match what a reader sees on the page. The headline should be the real title, the author should be a real person or organization named on the page, and the dates should be accurate. Use dateModified only for meaningful updates.
It helps search engines and AI tools identify who wrote what and how current it is, which supports trust and AI citation, but it does not by itself make a page rank. Link the author and publisher to proper entities, for example through organization schema, to keep the markup consistent across the site.
Related: Structured Data, AI-Readable Content, Technical SEO.