Law is Order, Routine, and Stasis. Cosmic Lawful beings want everything to function like clockwork simply for the purpose of everything and everyone having a place and purpose. Even if it's boring as all hell, it doesn't matter because perfect function and execution is the highest form of beauty to them.
Chaos is Magic, Change, and Instability. Cosmic Chaotic beings experiment with the essence of reality and create new life, new places, new everything according to their current whims and then those creations are imbued with their own will that causes them to rebel and create new things themselves and so on. Nothing lasts long, but that's ok because something exciting is always happening.
Those aligned with Balance are those that know the universe has to remain as it is, because either Law or Chaos winning would mean the destruction of life as we know it.
Like I mentioned, most people are Unaligned but Chaos and Law are VERY good at convincing mortals that their side is the right one, offering them riches, powers, technology, and command over certain aspects of the universe to gain any advantage over the Eternal Fight.