This indicates the highest level at which the vendor may set their reserve price. The reserve price is the price below which the property will not be sold. The vendor may set the reserve price wherever they wish, but they may not set it above the advertised figure. The reserve price itself will not be disclosed.
If the bidding does not reach the reserve price, the property will not be sold. If bidding reaches or exceeds the reserve price, the gavel will fall to the highest bidder.