To change the the title, description, and the text associated with your Discourse site in search engine results, you can configure the following settings on your Admin → Site Settings page, under Required:
Title- The name of this site. Visible to all visitors including anonymous users.Site description- A description of the site. This will be included in the meta description and shown in search engine snippets.Short site description- A short description of your site a few words.
For reference, we also have a Discourse SEO overview (sitemap / robots.txt ) guide that has additional information on Discourse’s SEO features and how these can be configured.