Custom Keywords are used by some search engines for indexing your website. Keywords should be in a comma-separated list (eg: hockey, sport, NHL).
The Description will be used in the meta tags when people or search engines visit your website. Most search engines will use the description for a summary in their search results.
Note: The meta tag information added here will be specific to the page you're modifying the settings for, and not for your entire site! To create meta tags for your entire site, please add them to the Keywords area in the Head Tag section of your Site-wide Settings.
Where to Find
Clicking the "SITE" button in the main toolbar, as in the below image, will bring up the "SEO" option in the menu.
Note: Page-specific SEO settings can also be managed in the "PAGES" section of the Toolbar. Here you can select the cogwheel icon on the page you wish to manage to bring up the "SEO" sub-menu.