common bean; green bean
Refers to the common bean (Phaseolus vulgaris), especially the immature pod eaten as a vegetable. The name comes from the fact that it can be harvested three times a year.
See also: いんげん豆
Common beans are delicious when quickly boiled and dressed.
At this time of year, the common beans in the field are growing well.
さやえんどう is the standard Japanese word for snow pea/mangetout; 三度豆 is a dialectal synonym in Fukushima and Niigata.
From 三度 (three times) + 豆 (bean), referring to the plant's ability to be harvested three times per year. The dialectal sense for snow pea likely arose from a similar appearance or usage.