You must be using "Classic" customer accounts for your store to use this template. To learn more about the difference between Shopify's "New" and "Classic" customer accounts, take a look at their Customer accounts documentation.
The Addresses page is where customers can update and manage their shipping addresses. There's one "default" address. Customers can always change their address at checkout, this default address is the one that comes up first. It looks like this:
This template works like other templates where you can also add other sections to it.