"It is therefore utterly false to say that Marx revokes the law of value as far as individual commodities are concerned, and maintains it in force solely for the aggregate of these commodities"

Rudolf Hiferding's quote is referring to the law of value as proposed by Karl Marx. Marx argued that the value of a commodity is determined by the amount of labor that entered into producing it. Hiferding is saying that Marx did not withdraw this law for individual commodities, but rather kept it for the aggregate of commodities. To put it simply, Marx believed that the value of a commodity is figured out by the amount of labor that entered into producing it, however also that the value of a group of commodities is identified by the overall quantity of labor that went into producing them. This quote is highlighting the importance of the law of worth in Marx's financial theory.