Page Settings and Search Engines
How this page identifies itself in search results and when somebody shares it.
Settings in the editor toolbar covers how this page is identified rather than how it looks: its address, what search engines show, what appears when somebody shares it, and whether it should be indexed at all.
These default to your site-wide values, so a page you never touch here is still correctly described. Setting them per page is how you improve on the default.
Steps
Check the page title and address
Page Title is the page's name. The URL Slug is its address.
Changing a published page's slug changes its address, which means anything pointing at the old one now points at nothing — your own links, other people's links, search engine results. If you do change it, set up a redirect from the old address so nobody lands on a 404.
Write the meta title and description
Meta Title and Meta Description are what a search engine shows. They are not the same as your page's headline, and they should not simply repeat it.
A headline can afford to be intriguing because the reader is already on the page. A meta title cannot — it is competing with nine other results, and it has to say what the page is. Write the description as a reason to click rather than a summary.
Leave them blank and the page falls back to your site defaults, which is fine for minor pages and a wasted opportunity on important ones.
Set the featured image
Featured Image is what appears when the page is shared — in a message, on social media, in a chat. Browse Media picks from your library.
There is an OG Preview showing roughly how the share will look. Use it: a share preview with a cropped or missing image is a link people do not click.
Use the canonical URL only when you need it
Canonical URL tells search engines that this page's authoritative address is somewhere else. Leave it blank unless you have a reason.
The reason, when it exists, is duplication: the same content reachable at more than one address, or republished from somewhere else. Setting it wrongly tells search engines to ignore the page, so leave it alone if you are unsure.
Decide whether it should be indexed
Indexable by Search Engines is on by default. Turn it off and the page asks search engines not to list it.
Turn it off for pages that exist for a specific audience rather than for the public — a campaign landing page you are sending traffic to directly, a thank-you page after a form, an internal reference. The page still works and is still reachable; it just should not be a search result.
Result
A page that describes itself correctly in search results and shares, and is indexed only if you want it to be.