They don't physically print the notes, but they do magically add money to a person's account when they take a loan. That kind of thing is where most "money" (in banks, anyway) comes from.

It's just like matter and antimatter being created at the same time, money and anti-money (debt) are created at the same time and when they meet, they cancel each other out.

So borrowing literally creates money (and debt), and repaying debts literally deletes money (and debt).