Show, don't tell. What does it mean to you?
Ooh. Good question. I think it means the same thing to me it means to most genre writers. Let your characters tell the story by doing things and saying things. Don't over-narrate. If your protagonist is a fighter, don't tell me she's a fighter. Make her fight someone -- or many someones. If someone is sad, don't tell me he is sad. Show me what being sad looks likes. Above all, for me at least, it means remove myself from the work as a writer as much as possible, and let the story belong to the characters as they experience and react to it.