Assuming the file is legitimate and not a virus, here is what a trainer for Generals typically offers. Since "18" likely refers to the number of options included, this would be considered a "Mega Trainer."

Trainers are intended for Single Player use. Using them in multiplayer environments can result in "out of sync" errors or bans on official servers. Command & Conquer: Generals Cheats and Trainer

: Buildings are completed immediately upon being placed, rather than waiting for the construction timer.