These plans were attempts to help Germany be more able to pay the reparations that it had been forced to pay by the Treaty of Versailles. The Dawes Plan came first and was replaced by the Young Plan when it failed.
In both cases, the plans tried to help the Germans by creating payment schedules for the reparations debts that would be easier for Germany to meet. There were also attempts to help Germany stabilize its economy so that it would be able to have the economic growth that would allow it to pay. The two plans both leaned heavily on US aid. The Dawes Plan relied on American loans to Germany and the Young Plan relied on America's being willing (which it ultimately wasn't) to forgive the debts that other allied countries had borrowed from the US during WWI.