This will largely depend on the how much food source there is for bees in an acre of land. We would suggest consulting with your local beekeeping association to find out what's an appropriate number of bee hives to have per acre of land.
One important thing to keep in mind is the importance of having a variety of nectar sources. Bees can't survive on a single nectar source. The lesser the variety, the further the bees need to forage in order to get what they need.
If you are new to beekeeping then it may be best to take a gradual approach where you start off with a small number of bee hives. You could, for example, start off with about ten to twenty hives and increase this number until you start to see a lower volume of honey output per hive.