From the game
Syntax: BOMB <player> <target_id> MP: 25 This will launch your air units against the given player. The end result will be one of the following if you win: A building will be destroyed, Farmers will be killed or you will not be able to bomb due to weather. The <target_id> is an optional field and can only be used in certain circumstances but it allows you to specify a building in a nation to bomb
You can really ruin someones day with bombing if done correctly. If you bomb blindly you get a chance to hit the player's farmer population itself, or if you combine this with the Recon Spy you can specifically target particular buildings. Currently your bombers can strike up to 5 times in an attack if you have up to 5 bombers to attack with. That is 5 potentially destroyed targets.