nothing to be afraid of; trivial; not amounting to much
A fixed expression used to dismiss something as insignificant or not worth worrying about. Often carries a defiant or contemptuous tone. The literal meaning is 'what can (it) do?'
No matter who the opponent was, he faced them as if they were nothing to be afraid of.
この程度の困難、何するものぞ。
This level of difficulty is trivial.