The footer newsletter sign up module adds an email opt-in form to your footer so that users can subscribe to your newsletters.
By default, the plugin will add users to the Lightspeed subscriber list, but you can also let users subscribe to Mailchimp instead. Please check the Mailchimp integration for more details.
You can also override the text above the newsletter signup form and below, by going into Content > Translations and override the text you wish to wish to change. See this link for more information.