Auto-translated
Fairness is translated from English as "Justice."
I don't play Heroes 5 and have never seen the map editor, but I understand that this is an option that balances the map, for example, by evenly (i.e., fairly) distributing artifacts, castles, or neutral creatures on the map.
Sorry if I'm wrong :o.
And here's the link:
http://www.maps4heroes.com/heroes5/random_map_generator_eng.php
Basic fairness means: isomorphic maps (that is, for each area there is a corresponding area for the opponent) with similar objects. The number and kind of objects may vary. For instance, if you encounter an area with several stat-improving buildings (like a Marletto Tower), your opponent will have at least some stat-improving building in his corresponding area as well.
Also, with basic fairness, both sides receive an equal number of towns (throughout the map), roughly the same mines, and roughly the same objects in the starting areas.
Advanced fairness: both sides have the same border guards between areas, and also, exactly the same guards guarding the key objects in the starting area (like wood and ore mines).
Expert fairness: the "too fair to be fun" setting. Both sides get exactly the same objects in their corresponding areas, as well as similar guards (as above). The main difference is which artifacts you find; this setting only guarantees the same number of, say, relics in the corresponding areas.
The main means of fairness: isomorphic maps (that is, for each area, there is a corresponding area for the opponent) with similar objects. The number and type of objects may change. For example, if you encounter an area with several stat-improving buildings (like a Marletto Tower), then your opponent will have at least some stat-improving building in his corresponding area as well.
Also, with basic fairness, both sides receive an equal number of towns (throughout the map), approximately the same mines, and approximately the same objects in the starting areas. Advanced fairness: both sides have the same border guards between areas, and also, exactly the same guards guarding the key objects in the starting area (like wood and ore mines).
Expert fairness: a "too fair to be fun" setting. Both sides receive exactly the same objects in their corresponding areas, as well as similar guards (as above). The main difference is which artifacts you find; this setting only guarantees that the same number of, say, relics are in the corresponding areas.
P.S. Supported by http://yandex.ru and http://translate.ru
Added after 59 seconds
I was right)