A bank is a company that works with the money that the people give it. If you give your money to a bank, it not only protects it but pays you interest so that it can work with the money. This is one of the reasons why people save their money in a bank. Money may also be safer there than at home.
Banks also lend money to other businesses and customers. They collect extra money called banking fees with which they pay interest to savers as well as salaries for their workers. Banks make a profit because they collect more interest than they pay to savers.