What is one or does it do i think my atlas lathe came with one. And my
newbie to the machining side doesnt really get the point of it currently

there is an electric motor attached ot a belt drive attached to an arbor
that ends in a small grinding attachment i assume this is essentially a
toolpost grinder?

But the application of one is still a bit of a mystery to me and i could
stand to be pointed in the right direction.