I'm not sure as I haven't read this specific short story in detail. But generally, it might be about a man who is quiet, perhaps his inner thoughts, his relationships, or the events that happen around him in a rather subdued or introverted context.
Since I don't know the exact content of 'the quiet man short story', I can only make some educated guesses. It might tell the story of a man who is quiet by nature. His quietness could be a source of mystery for those around him. The story could explore how his quiet demeanor affects his interactions with others. For example, he may be misjudged by more outgoing characters. Or perhaps his quietness is a shield that he uses to protect himself from a difficult past or present situation. It could also involve his attempts to break out of his shell in certain situations and how that changes the course of the story.