This bonus is a reward the country pays from its budget when a citizen finishes a new building. The value is how much each reward pays out.
Raising the value pays a bigger reward each time, which makes the rewarded action more attractive but spends the country budget faster.
Lowering the value pays a smaller reward each time, which saves the country budget but gives citizens less incentive.
This is a neutral explanation to help you decide — it doesn't favor either side.
Um bonus como esse e bom, mas nao dura muito.
It applies to any new building in the game, including roads. Also the building which was built on the same tile as the previous buildings triggers the bonus, so I suggest you approve the bonus.