Source: Player's Handbook
You have studied languages and codes, gaining the following benefits:
- Increase your Intelligence score by 1, to a maximum of 20.
- You learn three languages of your choice.
- You can ably create written ciphers. Others can't decipher a code you create unless you teach them, they succeed on an Intelligence check (DC equal to your Intelligence score + your proficiency bonus), or they use magic to decipher it.