It's possible it's:
* A misspelling: Perhaps you meant a similar-sounding word like "swang" or "shang".
* A slang term: It might be a regional slang word or a term used within a specific group.
* A made-up word: Someone could have created it for a fictional story or joke.
To understand what "shwang" means, you'd need more context. Please provide more information about where you encountered this word, or what you were trying to say.