EC for Iron is 1s2 2s2 2p6 3s2 3p6 4s2 3d6

The 4s orbital being fully filled is higher in energy than 3d orbital. So it can give 2 electron(valence electron) of 4s orbital and thus has valency of +2. But sometimes it also gives 1 electron of 3d orbital(as half filled orbital are more stable than unevenly filled orbital) thus sometimes its valency is +3.

So Iron has valency of +2 and +3

The 4s orbital being fully filled is higher in energy than 3d orbital. So it can give 2 electron(valence electron) of 4s orbital and thus has valency of +2. But sometimes it also gives 1 electron of 3d orbital(as half filled orbital are more stable than unevenly filled orbital) thus sometimes its valency is +3.

So Iron has valency of +2 and +3