Variegated refers to having multiple colours or colour patterns. This usually means streaks, edges, or blotches of contrasting colour. Some variegated plants are specifically bred for these differences in colour/patterns as it adds to the visual appeal and attractiveness of the plants and garden.
Variegated plants occur for a variety of reasons including virus infections, but mostly it is due to genetic variations. Despite some variegated plants being more sensitive to light and temperatures, we tend to protect and perpetuate these genetic variations because of our interest in the unusual.
Examples of variegated vegetables include peppers (like the fish pepper in the photo above), tomatoes, and even watermelons!