Monkeys are animals mentioned in the DreamWorks Dragons Franchise.
Most species of monkeys are arboreal, which means they spent most of their lives in the trees. There are some, like the baboons who live on the ground. All the monkeys are diurnal and most of them are very intelligent.
"Albino Snow Monkeys" are specifically named in the Franchise. There is no species in reality with this name, but there is the Japanese Macaque (Macaca fuscata) which is sometimes also referred to as a "Snow Monkey". They have white coats and are the northern-most occurring monkey species, living in Northern Japan.
It is not stated if monkeys do have a function in the franchise.
In reality, monkeys can be kept as pets. Many of the higher intelligent species can be trained to do intricate tasks which aid humans in important work. They're also commonly used in entertainment such as circuses and street vendors. Some monkeys are even used in experiments in place of humans since they are biologically close to humans.
|“||You think I'd be dragging your monkey butt all over the jungle risking your life if my brother weren't the most important thing in the world to me?||”|
|— Ruffnut to Snotlout|
|“||Legend has it the old Nut family tree originated with the wild albino snow monkeys of the Northern Territories.||”|
|— Tuffnut telling his origins|
|“||If I tell that gorilla what happened, that he wasn't actually saved by Ruffnut, but in fact he saved her, then maybe, just maybe, he'll sail back to his own rock and then we can go back to our perfectly normal life.||”|
|“||This feed is untouched by human hands, p-picked and p-packaged by Nordic howler monkeys.||”|
|— Chicken Feed Salesman to Snotlout|
There is no species named "Nordic howler monkeys", however there is are species of howler monkeys, belonging to Genus Alouatta. All species are native to South and Central America and do not occur in Europe.