The scale of balance is half a gaint golden scale. The other half of the scale is not present and the counterweight is located somewhere else, presumably somewhere in the divine realm of Ratish . When the scale is not balanced the devote worshippers of Ratish that house in a village nearby the scale balance the scale by pouring sacrifices to Ratish in the scale. The weight of these sacrifices does not seem to matter when influencing how low the scale sinks, instead the worth of the sacrifices to the individual sacrificing it seems to matter how much the scale is influenced.
No mortal knows what the scale is balanced against, but Ratish has promised that mortals who help to balance the scales will be rewarded in the afterlife.
Some theories about what the scale is balanced against include the Tellurian village on the Highest mountain in Midgard since the scale of balance is located on the highest of the kildal peak its peaks.