'Year-round' means happening or open or available through every season, not only in summer or only in winter. It works two ways. Before a noun it is an adjective: a year-round resort, year-round sunshine, year-round employment. After a verb it acts like an adverb, and then people often drop the hyphen: 'The pool is open year round.' The heart of the word is contrast — you use it when a listener might expect the thing to be seasonal. Saying a market is year-round tells you that it does not shut in winter like other markets do. Saying someone works year-round tells you they are not a summer-only worker. So it is very common in tourism, farming, sport, and job talk. Compare it with 'year-long': year-long is about a length of twelve months; year-round is about covering all the seasons, and can go on for many years. A year-round hotel has been open every season for twenty years.