noun
side dish; vegetable dish
Refers to a dish served alongside the main staple (rice, bread, etc.), often a vegetable or small prepared item. Common in compounds like おかず (お菜) and 総菜.
今日の菜は、ほうれん草のおひたしです。
Today's side dish is spinach dressed with soy sauce.
この定食には、ご飯と味噌汁と菜が二品つきます。
This set meal comes with rice, miso soup, and two side dishes.
総菜 refers specifically to prepared side dishes sold at delis or supermarkets, while 菜 is a broader term for any side dish.
The kanji 菜 originally referred to vegetables or greens. In Japanese, さい came to mean a dish that accompanies the staple food, often vegetable-based.