Provinces are the "board tiles" of the strategic shard map. They can be conquered, built up and navigated with heroes. Each shard has numerous different provinces. (which and how many depends on shard type and size). Minimum shard size has 36 provinces while maximum shard size has 400 provinces.
Conquered provinces provide income and resources. They can be explored for locations which can be visited by heroes. They grow in population and may rebel in bad mood.