These look and grow very much like their close relatives of edible cabbage and kale. Although they're categorized as the same species (Brassica oleracea) as the edible varieties and you could eat them, the ornamental versions have been bred for looks, not flavor. Their leaves feature purple, rose, and creamy white colors, making them look more like large flowers than vegetables.
Ornamental cabbage and kale look especially good in a large grouping or as edging for a garden bed, where their purplish hues blend well with other fall colors. Growing the ornamental versions is not much different from growing regular cabbage or kale.
The plants prefer to grow in full sun. However, when grown in warmer climates, partial afternoon shade is ideal.
Keep the plants well watered; they like soil that's consistently moist but not soggy. If the top inch of soil is dry, it's time to water. If your usual cool-weather climate includes rain, you probably won't have to water at all. But be prepared to add supplemental water during a dry spell.