Static balance is concerned with the rules of the game and how they interact with each other. These are specifically time invariant. In other words, these are the rules of the game that can be written down and documented to aid play—the usual strategy guide fodder.
A concrete example would be a comparison of the relative strengths of units in a war game, or the average jumping distance of Mario in relation to the average distance between platforms. Generally, when game balance is spoken about, most people are unconsciously referring to the static balance (sometimes mixed with a little of the dynamic balance).
Static balance is the classic game balance that is talked about in other books, including Game Architecture and Design