Email notification enables you to send out email when user submit the corresponding HTML form.
Navigate to Forms tab and click on the gear icon against the form in All Forms widget, which takes to the forms settings page. Scroll down to Email Notification widget, to receive email notifications make sure Enable Email is enabled. Enter the recipients email addresses to which notification to be sent, then save the changes.
After the changes saved, recipients will receive an email when a user submits the form.