The name of the function, what goes in and what goes out in most cases should be enough to get a good idea on what the function does.
It also helps to make a diagram of how everything ties together. Just boxes and arrows is enough.
When writing your own code, it takes a bit of experience to know when to put something in its own function. It's very obvious when you're replicating code. It's also very common to cut things up when a function gets too big. Look for bits of functionality that you can give a good name.
I doubt Trump puts so much thought into his choice of words.