Is it possible to dimension and label an angle in sketchup free?
There is no native tool for dimensioning angles. You can draw a sort of dimension using the Line and Arc tools and then use the Text (not 3D Text) to add the actual text. FWIW there is no native angle dimensioning in the desktop versions of SketchUp, either. There is an extension that will create them however.
This is done in SketchUp Web.