The SPECIAL-NAMES paragraph:
Relates IBM-specified environment-names to user-defined mnemonic-names
Relates alphabetic-names to character sets or collating sequences
Specifies symbolic characters v Relates class names to sets of characters
Specifies one or more currency sign values and defines a picture symbol to represent each currency sign value in PICTURE clauses
Specifies that the functions of the comma and decimal point are to be interchanged in PICTURE clauses and numeric literals
Why don't you take a look at the documentation on the SPECIAL-NAMES paragraph and the topics that follow it in the manual. They can explain much more clearly.
If you still have some specific questions, feel free to ask them.