Molarity or molar concentration of a substance in a solution is the number of moles of the substance in one liter of the solution made using it.
We are given that the solution of KCl initially has a molarity of 1.95 M. This means that 1 liter of the solution has 1.95 moles of KCl. Or 175 ml of the substance has 175*1.95/100 moles of KCl.
When the solution is diluted to 635 mL, the 0.175*1.95 moles is present in 635 mL of the solution. The molarity changes to 0.175*1.95/0.635 = 0.537 M
The new molarity of the solution that is obtained finally is 0.537 M.