Netlify Edge Functions allow for A/B testing by splitting website traffic between two versions of a page or user journey using browser cookies to assign users to test buckets. This approach can modify statically pre-generated pages at the time of the request, avoid the "flash of unstyled content" (FOUC) issue, and provide consistent experiences throughout browsing sessions. The Edge Functions can be used with any front-end framework or no framework at all, making it a flexible solution for A/B testing. To implement this, users need to create an edge-functions directory in their Netlify project, write the necessary code to assign users to test buckets and decide which page layout is served based on the cookie values, and track test variants using analytics tools like Google Analytics.