Okay, let me explain it to you like you're 5! So you know how when you go to the store and want to buy something, you use money to pay for it, right? Banknotes are a special kind of money that are made by banks, and they come in different sizes and have different colors.
The banknotes of the Hong Kong dollar are the special money that people use in Hong Kong instead of regular money. They have some special features that make them different from other banknotes. For example, they have pictures of important people from Hong Kong on them, like famous politicians and leaders.
Another thing that makes them different is that they are made from a special kind of paper that is hard to copy. This is important because banks want to make sure that people don't make fake money and try to use it to buy things.
Now, let's talk about the different sizes and colors of the banknotes of the Hong Kong dollar. The smallest one is called the $10 banknote, and it is blue. The next one is the $20 banknote, which is green. The $50 banknote is purple, the $100 banknote is red, and the biggest one is the $500 banknote, which is yellow.
So when people in Hong Kong want to buy something, they can use one of these banknotes to pay for it. They can also use coins, just like we do here, but the banknotes are more convenient for bigger purchases. And that's how the banknotes of the Hong Kong dollar work!