I would like to know what the different languages my PC can automatically have. I play Advanced Dungeons and Dragons 2nd edition and my PC has a 12 Intelligence.
That entirely depends on the setting your DM is using or has created.
Apart from setting-specific languages, it is typical (though not guaranteed as it's again up to your DM) for there to be one language for each major race; i.e. elvish for elves, goblin for goblins, dwarvish for dwarves, etc., etc. This is typical of AD&D simply because such "racial languages" are mentioned in the write-ups for the playable races in the Players' Handbook and the entries for creatures in the Monstrous Manual.
When considering what languages to choose, always consult with your DM.