Year is a unit of time that refers to the orbital period of the Earth moving around the Sun.
The term "year" can also mean:
1. A period of 365 or 366 days, divided into 12 months
2. A period of time associated with a particular activity (e.g. school year, fiscal year)
3. Age or time of life (e.g. "She's 10 years old")
4. A very long time (e.g. "I haven't seen you in years!")