The golden hour is the first or last hour of sunlight, when the quality of the light allows for some spectacular photos. Here is an example from Everafer Images that shows what can be accomplished by a skilled photographer.
Be sure to discuss this opportunity with your photographer before deciding on a ceremony time. They will be happy to give you guidance on scheduling your ceremony in order to allow sufficient time afterwards for photos that take advantage of this special light. You may want to consider having your ceremony end about 45 minutes to an hour before sunset. This provides plenty of time for your photographer to capture photos of your family and bridal party, as well as some special photos of the two of you, freshly married!