野菜, or also seen as やさい (pronounced yasai) means vegetables.
At RyuDai 琉大 (short for Ryukyu Daigaku 琉球大学, the University of the Ryukyus), there is an occasional vegetable stand by the “Welcome Plaza” at the Nishihara/South gate (西原口, also labelled 南口). It is run by the agricultural department field studies. The vegetables are grown in the fields at the school and are mostly local types of vegetables like goya, okra, ensai, carrots, and such.
I am not sure if there are any actual set open times, but I know it is open when I see the flags with “野菜” out at the Welcome Plaza. The only times I have noticed it open is around lunch times. Last time I bought a bag of okra and some enormous goya; the prices are pretty cheap for what you get. I should remember to try to stop by there more often, but I usually forget about it since I usually use the East gate (東口) or the North gate (北口) instead.