The Internal Program Environment simply allows you to see what internal objects (modules, subroutines, messages etc..), external
objects (tcodes, reports, function modules etc..), internal operations (READ, MODIFY, DELETE) and external operations (SELCT, MODIFY etc..)
a ABAP prgram uses.
To access it go to transaction SE38 and select the 'Utilities->Internal Program Environment' option
On the next screen simple choose the objects/operations you want to query