Question

Charlie deposits, or invests, his paycheck in a savings account. the bank can then offer some of the money to a borrower in the form of a loan. how can charlie benefit financially from this relationship?

Answer 1

Charlie can benefit from this relationship by having his money in a savings account and it being used to offer someone a loan because the loanee has to pay interest for the loan and some of this interest goes to pay Charlie though interest on savings accounts is usually quite low unless it is a special like a jump start savings account such as is available at some credit unions,

Answer 2

In this case, Charlie could benefit financially because Charlie can earn interest on his original deposit.
One of the things that Bank used to attract saving from the people is by offering interest rates for the total saving amount. Which means, the amount of money that Charlie deposited in the bank will grow in value based on the the rates that appointed by the bank (minus the service charge)