30% off means the price of an item or service has been reduced by 30%. This is a common discount used by many stores and businesses to attract customers and increase sales. In some cases, the discount may be applied to the original price of an item or service, while in others it may be applied to a discounted price. For example, if an item was originally $100 and then discounted to $80, a 30% off discount would reduce the price further to $56.