When the Fed says they are raising rates from 0% interest rates to 25 basis points. How have lenders made money off 0% interest rates ?

When rates were 0% interest rates who is getting these 0% interest rates is it the banks? because when I google the average mortgage rates it’s says 3.99% interest so what does this mean when they are saying this?

Is 25 basis points really going to do anything to the economy, why don’t they raise rates atleast 1%?