[Fvn]

I think its a cantilevered platform that allows them to move materials in/out of the floors via the tower crane. Jumping with the screen as floors get added.

Its just laid on its side in that picture I believe the wood part will be horizontal once set on the building.

I could be wrong but I don't think there's any need for formwork that big on the outside of the building. The big columns are formed above the screen...