The phrase "to make up" has multiple meanings depending on its context.
1) To create or come up with something new, such as an idea, plan, story, etc.: For example, "I had to think fast and make up a lie to get out of the situation."
2) To repair or fix something that is broken: For instance, "We need to make up the bed before our guests arrive."
3) To reconcile or become friends again after an argument or disagreement: As in, "They finally made up and became close friends again."
4) To apply cosmetics to enhance one's appearance: For example, "I need to make up my face before the photo shoot."
5) To compensate for something that was missed or lost: Such as, "We will have to make up the class we missed due to the snow day."