This linguistic confusion is why Americans call the Pennsylvania Dutch Dutch even though they're Germans. To review: this country is the Netherlands, its people are Dutch, they speak Dutch. There is no country called Holland, but there are provinces of North and South Holland.
In clean, uncrowded conditions in tanks or ponds, goldfish grow fast. They can grow to a few inches (1 to 4 inches) within the first year. It really depends on their genetics and living situation. It may take a year or two before they change color from brown to gold or whatever color their parents were.
Goldfish are actually very complex creatures. Amazingly, they can reach lengths of 12 or more inches and live 10 to 20 years. The oldest goldfish on record was over 40 years! Goldfish are among the hardiest of fish, and can survive through the worst of conditions. They are perfectly adapted to life in a pond, just like their wild carp ancestors.