Okay kiddo, let me explain to you a person named William F. Sharpe. He is a really smart man who is famous for his work in finance and economics. He came up with something called the Sharpe Ratio which helps people to figure out if they are making good decisions when they invest their money.
Imagine you have some chocolates that you want to share with your friends. You want to make sure that you give them a fair amount of chocolates depending on how much they helped you. William F. Sharpe made a tool that helps you to figure out how much chocolates your friends should get depending on how much they helped you.
In the adult world, people use this Sharpe Ratio to figure out how much money they should invest depending on how risky or safe their investment is. The higher the Sharpe Ratio, the better the investment is because it means that the investment has a good return (more chocolates) with low risk (less chance of losing chocolates).
So, William F. Sharpe is like a superhero for investors who helps them to make good decisions with their money by using the Sharpe Ratio tool.