This is a MailChimp embedded naked form, copied into the text tab of a page template.
In the social media links in our customizer, you can link to a page like this, with a URL ending in /subscribe, and it will automatically add an envelope icon for you, as shown above in the icons menu to the right of the sidebar.
You can also purchase a pop-up newsletter subscription prompt, via our Newsletter Pop Up plugin! Click “POP UP PLUGIN” in the menu underneath Pearl’s logo, above, to view a demo. Sold separately.