tldr: Your character doesn't need to know the name of the language for your player to write it on the character sheet.
I'm looking at the following comment:
@HeyICanChan the former (How can a creature put the correct name to a language the creature doesn't itself "speak"?) is my intent. Once you know what language you want to learn you just put a point in linguistics and poof you know the language.
There's an interesting mix of character knowledge and meta-knowledge/mechanics here. If I understand correctly, you're basically asking "How can my character learn the name of the language (character knowledge/in-game action) so that the player can put a point into linguistics (meta-knowledge/game mechanics)?"
I'd like to suggest a frame change here. If we look at the hypothetical of your friend learning aboleth, there are two simultaneous, separate, and connected things that would happen. In the game world, there is the act of the character learning a language, with time spent studying, speaking, and listening. In the meta-game / game mechanics world, there is the act of your friend putting a rank in linguistics and writing "aboleth" on a character sheet. The game mechanics act (writing on a sheet) is representative of what happens in the game world (learning and studying).
I know of no requirement that your character know the name of a thing before you can put it on your character sheet. On the meta-game side, your friend knows that the language is aboleth, and can write that on their sheet with no problem. In-game, your character might not initially know the name of the language, but would pick it up as they learned to speak. For a real life example, you could learn the basics of hello, goodbye, introductions, and basic grammar in a language before you learned enough to understand/articulate "the language you are speaking is ____".
However, this does highlight one real roadblock to your friend learning the language. It sounds like your character is unwilling/unable to teach the friend. In different editions of DnD, learning a new language or putting points into a skill can take time, money, or a trainer, often at the DM's discretion. I honestly don't know enough about pathfinder to be positive what the rule is there (although the SRD seems to indicate you can just put points into it). However, it would be very possible and appropriate for your DM to rule that the friend cannot learn the language without investing time, and/or without a willing teacher.