Free Shipping plugin is used to display the free shipping option ($0.00) for customer to choose.
You should use Free Shipping plugin in the case your store is free ship or if you would like to require customers to go to store to pick up their orders.
Title and Description of Free Shipping can be edited/translated by going to EShop -> System -> Translation, then filter by "PLG_ESHOP_FREE", you will see the variables for them. Simply edit and click on Save button on the toolbar.
Each Free Shipping is used to set shipping cost for one Geo Zone. In the case your site has different shipping costs for different Geo Zones, you should use duplicated Free Shipping plugins.
In the "eshop_unzip_first.zip" package that you received after purchasing EShop, go to folder "duplicated-shipping-plugins" you will see 5 duplicated Free Shipping plugins there.
Simply go to EShop -> Plugins -> Shipping, scroll mouse to "Install New Shipping Plugin"to install these duplicated shipping plugins one by one and configure them in the same with with default Free Shipping plugin.