The most common use for the word "bank" is when describing the place where money is stored, exchanged, loaned, or borrowed:
Bob needs to go to the bank and make a deposit.
If you need money to start your own business, you might be able to borrow some from a bank.
A bank might loan you money.
Many children put the money they receive in a piggy bank.
piggy bank
My nephew is thinking about going into banking when he graduates from college.
There are some other ways to use the word "bank."
The area alongside a river is called a "bank." In this picture, you can see a lot of large rocks on the banks of the river.
a river bank
People who play basketball often bank the ball off of the backboard in order to get the ball through the hoop.
Bank the ball against the backboard.
People who play pool usually know how to bank a billiard ball off of the sides of the table or off of other balls when trying to get a ball into a pocket.
They’re playing pool.
Finally, there’s an expression that people use when they want to say that something or someone is dependable or reliable and certainty is high:
You can bank on that.
A good college education can lead to a high-paying position within a company. You can bank on that.
Don’t bank on finding a place to park your car downtown tonight. All the parking garages will probably be full.
piggy bank 
a river bank 
Bank the ball against the backboard.
They’re playing pool.