The principle of charity means that when you are trying to understand what someone is saying or writing, you should try to be as nice and generous as possible in interpreting their words. This means that you should not assume that they are being mean or stupid or trying to trick you, but instead you should assume that they are trying to make sense and communicate clearly.
Imagine that your little brother or sister is telling you about something that happened at school. They might not use the exact right words or explain things perfectly, but you know that they are trying their best to tell you what happened. So you should listen carefully and try to understand what they are saying, even if they make mistakes or leave things out.
The same is true when you are reading a book or listening to someone else's ideas. You should try to understand what they are saying and assume that they mean well, even if you don't agree with them or think they are wrong. This doesn't mean that you have to agree with everything they say or pretend that their ideas are better than yours, but it does mean that you should give them the benefit of the doubt and not be too quick to judge or criticize them.
Overall, the principle of charity is about being kind and respectful to others, even when you disagree with them or find them difficult to understand. It's a way of showing empathy and compassion, and it can help you build better relationships and communicate more effectively with other people.