This option will not be used in 99.9% of cases. However, to achieve perfection, it can be used.
ESI allows caching parts of the page. For example, you can cache the shortcode “Similar Posts” even if the rest of the page is not displayed from cache.
Another example is that wp-admin is not cached for the administrator, but the Admin Bar can be displayed from cache.
ESI Nonces: allows you to automatically cache parts using nonce. Add a nonce to enable it. Of course, you first need to enable ESI in the first field.