Banking code is like a set of rules that banks follow so that they can take care of your money and keep it safe.
Think of it like a game of tag. When you play tag, there are rules you have to follow so that everyone can have fun and be safe. For example, you can't tag someone too hard, and you have to stay within the playing area.
Similarly, banks have rules they must follow to keep your money safe. These rules cover things like how much money you can take out at once, how long it takes for money to move from one account to another, and what kind of fees they can charge you.
So, the banking code is a way for banks to play by the rules and make sure that everyone's money is protected.