Red proso millet is a warm-season annual grass that can be used as a cover crop for a variety of purposes, including: 
Erosion control: Red proso millet can help control erosion
Weed suppression: Red proso millet can help suppress weeds
Livestock grazing: Red proso millet can be used as supplemental grazing for livestock
Soil builder: Red proso millet can help build soil
Nitrogen scavenger: Red proso millet can help scavenge nitrogen