a 'distro block' is a distrobution block. It splits a single wire into multiple wires, typically of smaller size..
ex. you have a 0 AWG wire from the battery.. it goes into the distro block. Then you have 2 4 AWG wires from 'the other side' of the block, one for each amp.
You can get blocks that are fused or unfused.. fused means there is a fuse between the main inlet and the outlets (one fuse per outlet usually).. non-fused is basically a big chunk of metal that has the inlet and outlets..
Distro blocks in a nutshell
you only really need a distro block if your main power wire is supplying more than one thing...
Hope that helps..