Says a message to everyone in the room in your racial language. All races have a unique racial language, except for humans, who speak basic as their native tongue.
If a player (or mob) understands your language, they will be able to read it. If not, they will see, what is to them, gibberish.
This command falls under the same rules as the standard <say> command. Plus, keep in mind that all wizards are fluent in all dialects.