Banks "get" money in a variety of ways.
1st of course is the money that investors or owners put into the bank to open it. Once upon a time that could be a significant amount of money, but in modern times it has been less influential.
Secondly banks earn money by charging interest on the money they lend out. They also make money by investing the money their depositors trust them with in speculative investments that hopefully would pay more than they would be obligated to pay in their savings accounts. And there are various and sundry, more or less piddly, income streams such as safe-deposit boxes, certified checks and other such activities.