Nourishment
Nutrition
noun, の adjective
Nourishing and fostering. The thing that gives you this is nourishment or nutrition.
滋養 is a formal and somewhat old-fashioned word. It's mostly used in writing to describe nutritious foods or the health benefits of supplements, tonics, or energy drinks.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
風邪を引いたら、大豆だとか林檎だとか、滋養のある物を食べなさい。
When you get a cold, eat nourishing food like soy beans or apples.