Here "a homer of barley" represents a piece of land that would need one homer of barley in order to plant on all of it. AT: "a piece of land that requires one homer of barley in order to plant all of it will be valued at" or 'the value of land that requires one homer of barley will be" (See: [[rc://en/ta/man/translate/figs-metonymy]])
If it is necessary to use modern weight units, here are two way of doing it. AT: "fifty pieces of silver, each of which weighs ten grams" or "five hundred grams of silver" (See: [[rc://en/ta/man/translate/translate-bweight]] and [[rc://en/ta/man/translate/translate-numbers]])