This tool can be used to encode and decode messages using a Al Bhed Language in Final Fantasy.
The Al Bhed are a tribal group of technologists in Final Fantasy x and Final Fantasy X-2. They have their own unique language (made up) which is a simple cipher. This Al Bhed translator will convert Al Bhed into English and English into Al Bhed.
Within the game, a player can learn thelanguage by picking up Al Bhed Primers. For ever primer you acquire, you will automatically see a translated view of a single letter of their alphabet. In Final Fantasy X-2, you will discover Primer by listening (to the language) or digging in the Bikanel Desert. In Final Fantasy X, Primers are given by NPC's or can be discovered in the field. The player can also use an Al Bhed Compilation Sphere to load Primers from another saved game.
This is pretty common, where a game maker uses a basic pen and paper cipher to create a faux game language.