The molarity of a solution is the concentration of the compound the solution has been prepared with in terms of moles of the compound per liter of solution.
A 18.4 M solution of H2SO4 has 18.4 moles of H2SO4 per liter of the solution. A solution with a molarity of 0.1 M has to be created. 600 ml of this solution has 0.1*0.6 = 0.06 moles of H2SO4.
Let the volume of 18.4 M solution of H2SO4 required be V. As the total volume of the solution is 600 ml, 0.6 - V l of water can be added to the H2SO4 solution. The molarity of the resulting solution would be V/0.6. This has to be equal to 0.10.1
=>V/0.6 = 0.1
=> V = 0.6*0.1 = 0.06 ml
The required volume of 18.4 M H2SO4 is 0.06 ml