If your titles or descriptions are all uppercase or varying cases in Shopify, you may not want the same format to be used in your Facebook catalog. Selecting this checkbox will change the format to lowercase.
On the Shopify product editing page, you can “Edit website SEO” which allows you to edit the page title, add a meta description and edit the product URL. This is what we refer to a “Search Engine Optimized Titles and Descriptions”. If you would like to use these titles and descriptions instead of the standard ones, please check the checkbox.
This helps facebook identify Shopify products by their ID number. By default, this is checked.
If you are using the native Shopify integration for the Facebook pixel then you need to make sure this checkbox is checked for it to retarget properly.
Checking this option will change the feed’s product id to the content_ids to match the facebook pixel data received on the product page.