What Article markup helps with
It tells Google the headline, the main image, who wrote the piece and when it was published and updated. Google can use this for the title, image and date it shows, especially in Top stories and Discover.
Google has no required properties for articles, but recommends the headline, image, dates and author. Give the author a name and, if you have one, a link to their profile page.
Dates and times
Use the real publish date and update the modified date only when you make a meaningful change. The generator adds your time zone, which Google recommends, so the date doesn't shift by a day for readers elsewhere.
Images
Use a large, crawlable image that represents the article. Wide images of at least 1200 pixels work best for Discover.