Hi I'm new to arduino and robotics itself. I have no idea what this giant green board is in the middle of the robot. I really need help!
It's a sheet of FR-4 clad in copper, with much of the copper etched off to form a PCB. That is then coated in green UV cured paint (solder resist) and components are attached.
Other things are then plugged into it.
What function it performs depends on what the designer designed it to do.