"%SAY( )" is a Dialog Processing Statement. This adds a text, in place, that indicates a character says a given text. The statement consists of 2 parts, separated by a ":".
%SAY(Character:Text)
The character part defines the character whose name is supposed to be used.
This must be a valid CharacterData > CharacterKey and can also be x0 > c0 and "player".
This can be any text.
Example:
%SAY(player:Hey!) -> PlayerName: "Hey!"