For example, I have a paper that says: "the atomic RMS distribution about the mean coordinate positions is 0.41 +/- 0.04 A for the backbone atoms and 0.82 +/- 0.04 A for all atoms"
And I have no idea what any of this means, I found several papers with this kind of information but none of them explain why this is relevant in order to understand the structure of a protein.