hope following help u out.
1. What is the cube_table in oracle
CUBE_TABLEextracts data from a cube or dimension (OLTP) and returns it in the two-dimensional format of a relational table, which can be used by SQL-based applications.
2. How to see the script of the cube table.
use TOAD or other tool to view code. i m using TOAD so we can see code of table.
3. On what basic we define the cube table
check below oracle doc as reference, hope this will help to answer ur question