Okay kiddo, imagine you have a toy that you really want to share with your friend. But your friend wants you to give them two of your toys instead. That doesn't seem fair to you, but you still want to share your toy. So you come up with a compromise - you'll give your friend one toy now and they will be okay with that. This compromise agreement you both make is called an accord.
Now, let's say you give your friend the toy and they say "thanks, but I still want my two toys." This doesn't seem right to you because you made an agreement. So you remind your friend of the deal you both agreed upon earlier. Your friend then sees you're right and is satisfied with the one toy they have now. This satisfaction of their end of the deal is called a satisfaction.
In the grown-up world, this is called an 'accord and satisfaction' where two parties make an agreement or compromise (the 'accord') that is then executed and fulfilled (the 'satisfaction') to avoid a dispute or argument.