Show Newsletter Section

To display the newsletter section, go to Storefront > Theme > Customize > Theme styles > Footer and check the "Show Newsletter" checkbox.

To view the changes scroll down to the end of the page to view "subscribe to newsletter" option

To find subscribers of the newsletter go to Storefront > Marketing > Email Marketing > Subscribers

Save and Publish

After making all the necessary changes to your header settings, don't forget to save your theme and publish it to apply the updates to your store.