Newbie question... I search for fare basis code and came up with a ton of different posts that say fare basis code... but not one that tells me what it is.

Can anyone point me to where I can find out about fare basis code. I have and upcoming trip with fare basis code: QLX3MTH and another one with fare basis code: SA3AN

What does that mean for me?
How do I decipher these codes?

Thanks