What does the Content Citizens factoin trait do and how useful is it?

It says: "-25% (SYMBOL) on Systems "

(I tried searching the website however the search feature seems to ignore quotation marks.)

My mistake. after getting in game and looking it up the one I was talking about is called "Expansionist". However, Content Citizens has a similar property. What Content Citiznes does is it reduced the Negative Approval collected by your population from being on harsh planets. So for example some of the more Harsh worlds like Toxic have a -8 or higher approval penalty per population you place on that planet. A faction with this trait will reduce the total negative approval collected on a system this way by 25%. 

It is an excellent trait for a faction like Horatio that start with Ecologist Government. This is becasue they are able to more quickly grow and populate all the planets in the systems they take due to their unique laws that support such a tactic. The reduced penalties for approval means your economy will not be crippled as quickly and you can prolong the need for approval buildings to offset it much later than other players will be able to. 

It reduces overpopulation Disapproval, the disapproval you get from filling the last few slots on a planet.

You are correct. The reduction only applies to the disapproval from overpopulation slots. It does not reduce the negative approval for hash planets as I once thought. 

Thanks guys! :)

Must say it seems pretty useless for the point expenditure.