C++ is a programming language. It's in widespread use, and is probably the most common compiled (translated to machine code before use, rather than during use), native (runs directly on the machine, rather than on a virtual machine like Java) language currently in use.
Programming skills are useful for anyone who has to think critically to solve problems. In order to program a solution to a problem, you have to think of it in terms of the simplest possible steps, and then implement them. Since the program does exactly what you tell it to (as opposed to what you wanted it to do), you are forced to pay more attention to the little finicky details than you normally would, which makes you a better problem solver in turn.
It can be applied to financial problems in two ways: Directly, it can be used to automate some issues. You won't be doing much of that as a manager, but it's useful to understand the limitations of the systems used, as well as having a basic grasp of what's going on under the hood. Indirectly, it will allow you to more effectively communicate the minutia of a problem to others, as you will have had practice in defining problems in terms that a computer can understand (and computers are pretty dumb in the end... Fast, but dumb).