Scouts look just like ordinary soldiers, but they have very different features.
They walk faster than all troops except Medics and Jeeps, and can fire while walking, just like the Waffen SS troops, and come with an M1 Carbine (although this starting weapon will be replaced by the M1 Garand if you have the Meritous Unit Commendation). They also display the progress of the next wave of Germans to come, so you can plan accordingly. These traits make the scout very useful for strategies that involve advancing. The scout costs 6 TP.
Scouts can also can spot enemies for Mortars, allowing them to fire without a direct Line of Sight, and potentially increase any Arty Strikes that you call by 1 round.
Scouts are excellent anti-infantry units once they rank up. They can fire volleys of up to 5 grenades/rifle grenades (This is commonly known as boomspam) Keeping the starting Carbine as the Scout's weapon is a good idea, but giving him a Tommy Gun or BAR is a good choice for suppresive fire.
Although scouts are supposed to be capable of detecting infiltrators within a 200 pixel radius and spotting enemy snipers, neither of these features have been implemented as of the current patch.