It is available on the App Web under
"The APPWEB URL"/Lists/"The list internal name"
But really you should access the list (CRUD items) via Client object model or REST.
The list is meant to be "hidden" to the users of the app, and it is upp to you to provide interfaces to work with items in the list
And just a clarification: You need to use SharePoint hosted app to be able to use SharePoint artifacts like Lists directly in the App project
Though this one tells another story:

While this below tells this story (MSDN):
SharePoint-hosted apps for SharePoint are installed on a SharePoint 2013 website, called the host web, and that have their resources hosted on an isolated subsite of a host web, called the app web. This approach enables you to reuse common SharePoint artifacts, such as lists and Web Parts. When you take this approach, you can use only JavaScript and you cannot use any server-side code.
Benefit: This approach enables you to reuse common SharePoint
artifacts, such as lists and Web Parts.
Consideration: You can use only JavaScript in the app, and you cannot
use any server-side code.
http://msdn.microsoft.com/en-us/library/fp179887.aspx describes different hosting alternatives and their ups and downs. (But it is surely not too extensive)
So, you could use a List also in the other hosting alternatives, it will be added to the App Web though.