The first letter of SAP authorisation objects is intelligently coded to represent the SAP module for which it belongs:
e.g. F_KNA1_BUK
A Assets Accounting
C Classification System
E Consolidation
F Financial Accounting
G Special Ledger
K Controlling
L Logistic execution
M Materials Management
P Human Resources
S Basis
V Sales and Distribution
If the second character is an underline, then this indicates this authorisation object is a SAP standard one.
Use transaction SU03, SU21 or table TOBJ, to list the authorisation objects in the system and drill-down into the authorisation fields and their possible values.
If using the tables, you may need the other related tables to pull the texts: TOBJ, TOBC (classes), TOBJT.