First, I think you refer to the installation guide here: https://github.com/OpenROV/openrov-software
Second: Are you aware that we have a ready made disk image for OpenROV? There is a Linux and (since today) a Windows solution to apply the image. You find the details here:
If you wan't to install node on your own for the sake of learning (that's a very valid reason!) you want to check a couple of things:
Based on you screenshot, you're looking for the common.gypi on your host machine (you laptop or PC). That indicates that you probably try to run the steps on this machine as well. This would be wrong, you would need to do this on the BeagleBone. (You probably have node already installed on your pc, therefore the error)
Give it a try and run the steps on the BB. If you still struggle, I can guide you further.