The solution for the problem is:
First, use the concentration of the volume of the thing you know to compute for the moles of that substance. Then, use the coefficient in the balanced equation to relay moles of that to moles of anything else in the chemical equation. Lastly, translate moles into mass by means of its molar mass, or into a concentration using the volume.
Applying what I have said earlier:
0.0133 L X 1.68 mol/L = 0.0223 mol KMnO4 X (1 mol H2O2 / 2 mol KMnO4) = 0.0112 mol H2O2
Mass H2O2 = 0.0112 mol H2O2 X 34.0 g/mol = 0.380 grams H2O2