"on board spends " is simply anything that you have signed for on board ship and has been charged to your "On-board Account" The full truth will be revealed on the last evening of your cruise and it might be advisable to have the smelling salts around. Regards Neil Dow.
Items signed for on your on-board account. Usually charged to a credit card at the end of the cruis.
When a cruise agent is advertising On board spend, it means they will credit your on board account with that amount of money. ie Give you free spending monet. Helps alleviate the bar bill.