Banks generate income through different product and services like one of the primary ways is by lending money to customers at a higher interest rate than the rate at which they borrow money from other banks or the central bank. The difference in interest rates, known as interest rate spread allows banks to earn a profit on the loans they make. Banks also charge fees for various services such as account maintenance, ATM usage and wire transfer. Banks may invest their own funds in various financial instruments such as stocks, bonds and real estate to earn a profit on their investment. Some banks generate income by providing advisory services to clients or by offering insurance products.
What do you mean by product? I have no idea that the bank has any products. Because I have always known that banks always provide various services like lending, processing international payments, keeping customer's money as collateral etc. the bank keeps the customer's money and then lends it to other customers and takes a high rate of interest from it and gives some part to the customer and keeps the rest for themselves. From here the bank makes most of their profit. And some other charges are taken from the customer like SMS charges, maintenance charges, credit/debit card charges etc but it they are taken annually. The bank earns a lot of income from here too