What does on fields o'er which the reaper's hand has pass'd mean?

The phrase "on fields o'er which the reaper's hand has pass'd" refers to agricultural fields that have been harvested, indicating that the crops have been cut down by a reaper. It evokes imagery of the cyclical nature of farming, where the act of harvesting signifies both the end of one growth cycle and the beginning of another. Additionally, it can symbolize themes of labor, loss, and the passage of time in relation to nature and human effort.