From The Heroes of Might and Magic III wiki

Scouting increase your Scouting Range

Recommended for: Secondary Heroes, esp. ones who have/are likely to also get some travel skills (Logistics/Pathfinding/Navigation) and/or the scouting artifacts (Speculum/Spyglass), or against Necromancers harassing you with the Cover of Darkness.

Level	Scouting Range
None	5
Basic	6
Advanced	7
Expert	8