To me, it means that it is just as difficult to hold onto your money as it is to make it in the first place, and that frugality is a virtue. That's the great thing about quotes such as this one. We're each free to interpret it a little differently to make it more pertinent to our own lives.
it means a amount you save. for example by bying a discount brand that's a dollar cheaper mean that you earn a dollar buy getting the cheaper one and it's like earning a dollar because of your smart decision of getting the cheaper one