The Barracks is the upgrade from the Outpost offering two new units. It still focuses on Manpower cost for units, now having the Sniper and Gröditz available. It can later be upgraded to the Arsenal.
The Barracks allows for the construction of Snipers, the answer to Chronite and in large numbers is quite effective at taking out Hover Tanks. It also features the Gröditz, a unit that can go head-to-head against a Phantom.
It is well-known that the Sniper is one of the most powerful units available in most areas of the game for their high speed and high range, high damaging weaponry. They are the king of 1v1s with proper micro and kiting.
If your enemy has little to no ground resistance, but a Saint is in the skies. The Gröditz is tanky and powerful enough to slowly but effectively drain down the enemy Saint forcing it to retreat or perish.