When someone is absent, it means they are not there where they are supposed to be. Think of it like a puzzle missing a piece. The puzzle is not complete because one piece is absent. When your friend is not at school, they are absent because they are not in their usual spot in the classroom.
Imagine you have a big jar of cookies, and one day you notice that a cookie is missing. That cookie is absent from the jar. You might wonder where it went or who took it. Similarly, when someone is absent, you might wonder where they are or why they are not with you.
Picture a soccer team ready to play a game, but one player is not there. The team feels different because that player is absent. They might have to play the game without them, which could be harder because everyone has a special role. Being absent means not being where you are expected, and it can make things feel a little different or incomplete.