explanation
A clear description that helps someone understand something.
An explanation is what you give when you help someone understand something. When your teacher explains long division, she breaks down the steps so you can follow the process. When you explain to your parents why you came home late, you tell them what happened and why.
Good explanations make confusing things clearer. They answer questions like “how does this work?” or “why did that happen?” A science book might explain how caterpillars transform into butterflies. A friend might explain the rules of a new card game. Your explanation of what happened at recess helps the teacher understand a playground disagreement.
Some explanations are simple (“I was late because I missed the bus”), while others take more detail (like explaining how photosynthesis works). The best explanations match what the listener needs to know. Explaining multiplication to a second grader requires different words than explaining it to a high schooler learning algebra. When someone says “that needs more explanation,” they mean they still have questions. When they say “thanks for the explanation,” you've successfully helped them understand.