SHOWING vs. TELLING is an empirical concept (meaning that it can be entirely subjective whether a scene deserves showing or can be told just as effectively). It emphasizes the superiority of dramatization, demonstration, enactment, and embodiment over mere telling. In To Have and Have Not (not such a great title btw), Hemingway could have told us something rather abstract-- "Shots were fired"-- but he chose instead to make us see and hear: "The first thing a pane of glass went and the bullet smashed into a row of bottles on the show-case wall to the right. I heard the gun going and, bop, bop, bop, there were bottles smashing all along the wall."
So when your work is critiqued with these hated words: SHOW DON'T TELL, think of these words:
And that's what you do. Just remember, however, that there are times when TELLING is okay. It's up to you, the writer, to determine what seems right in each instance-- because clearly one cannot SHOW the entire 100,000 manuscript.
(This post has been inspired by and in some instances, directly quoted from A Handbook to Literature, 8th Edition, by William Harmon and C. Hugh Holman)