Metadata helps structure polkadot.study. Docusaurs will create routes and pages from information of your tutorials metadata and e.g. set page headers. That enables users to navigate the website and also find your tutorial easier with search engines. That is why you are encouraged to update the metadata of your tutorial before submitting it.
Front matter in docusaurus, is a specially formatted text block that will resolve into specific DOM content or other structured data accompaning your tutorial. One example of a complete front matter for a polkadot.study tutorial is
keywords: [tutorial, polkadot]
description: Learn how to write your tutorial on polkadot.study
Look at the explanations below to learn about all those parts, and why you should add them.
Tags are used to categorize your tutorial. E.g. supplying polkadot.js in this front matter item will list your tutorial on the polkadot.js Tag Page and as well on the front page under "Study Paths -> polkadot.js"
Keywords are important for SEO, can be the same as your tags but can also differ depending on keywords you want to choose. If in doubt, just use the same as your keywords.
The description that will appear on tutorial cards under the title. Will also appear on search engines as a page description.
What difficulty level your tutorial has. Accepted values are either
How long it takes for an average reader to complete the tutorial, e.g.