The bits that you see attached to the hands are called support structures.
How the printer works is that a DLP (Digital Light Processing) projector projects a slice of the 3D model downwards onto a bath of liquid resin which contains a built plate. The area exposed to the light hardens and the build plate moves down into the bath by about 0.2mm where the process is repeated until the model is complete.
Depending on the shape and because the model is built on a plate, support structures have to be created to support the weight of the model. You can read more about this process
at Wikipedia under Photopolymerization.