Pair by association is when you connect two things in your brain because you think they go together. For example, think about a dog and a bone. When you see a dog, you might also think about a bone because dogs love to chew on bones.
Your brain creates a connection between the two things because you have seen them together so many times. This is like when you learn that a certain color goes with a certain animal or when you learn that certain words go together to make a sentence.
Pair by association helps your brain remember things better. If you remember that a dog goes with a bone, it will be easier for you to remember both things together. It's like having a secret code that only you know to help you remember things!