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.