i'm looking at specs for a guitar and it mentions pole spacing. what is that?
Its not really important, unless you are changing pickups. Pole spacing is the distance between the poles (or screws) in the pickup. Ideally, each pole on a pickup needs to be right under each string. With a stock pickup, the poles spacing should match the string distance. But, if you are replacing pickups, make sure the pickups you get match the string spacing for your guitar.
the outside width is usually important for lap sliders as a wide pole width and short scale makes slants easier.