"A table that extends another table is called a child class, and the table it extends is the parent class" - this is about halfway down in this link below:https://docs.servicenow.com/en-US/bundle/tokyo-platform-administration/page/administer/table-administ

Roles are used to control access to applications and modules in the application navigator. Each application menu or module has a role field that specifies which role is required to view it. Users who do not have the specified role or a role that contains it will not see the application menu or module. Roles can also be used to control access to other features and capabilities in ServiceNow, such as tables, fields, scripts, and workflows.
Reference = Enable or disable an application menu or module, Grant a role access to applications and modules, Controlling access to applications and modules.

Create table from template is not an option for creating a table through the Guided Application Creator. The other options are available for creating a table in the app. Upload spreadsheet allows you to import data from an Excel file and create a table based on the spreadsheet columns and rows. Extend a table allows you to create a child table that inherits fields and behaviors from a parent table. Create table fromscratch allows you to define your own fields and data types for a new table. Reference: Create tables
https://docs.servicenow.com/bundle/tokyo-application-development/page/build/guided-app-creator/concept/gac-t

"Application developers must select an application as their current scope context."https://docs.servicenow.com/bundle/tokyo-application-development/page/build/applications/task/t_Sele