The following is based on content cut from Generals 2 and has not been confirmed by canon sources.
With this building the morale of surrounding units is increased by the propaganda of the Asia-Pacific Alliance. The propaganda tower heals, repairs and increases the firing rate of allied units in the area.
Abilities and Upgrades
Heals/Repairs Units and Boosts Fire Rate within Radius
Increases Radius and Effectiveness of Propaganda Effect. Propaganda Tower Upgrade.
Increases heal rate and fire rate of propaganda effect. Purchased from Research Lab
Like many APA structures, this building has Chinese slogans on it. In the case of the Propaganda tower, it is "争取胜利" (fight for victory).