Space Banking is synonymous with "banking," and is just another reason that timeshares are more flexible than other vacation properties. If timeshare owners can't use their week one year, or if they want to trade their time at their home resort for time at another resort within the exchange network, they may Space Bank their week.
Essentially, they are putting their week into the exchange company's inventory to be stored until next year, or to be traded for time elsewhere. It is important for owners to understand that once they've banked a week, the occupancy rights for that week now belong to the exchange company. Someone else will be booked into that time slot, and it will no longer be available for use during that year. See Banking