Standard year (Earth-2356)

A standard year (SY), also known simply as a year or a cycle, is a measurement of time.

On Coruscant, a year is made up of twelve months spanning 365 days of 24 hours each with no leap years. The galaxy used a standardized dating system based off of the galactic capital Coruscant. By the time of the New Republic, the Galactic calendar started to use the Battle of Yavin as the epicenter on which to date years.

On certain planets, including Lothal, a year is divided into four seasons (spring, summer, autumn, and winter) characterized by specific meteorological or climatic conditions. The planet Lothal based its yearly calendar on a system known as Lothal Years. A being's age is usually expressed in years. The passage of a thousand years was referred to as a millennium.

Source

 * https://starwars.fandom.com/wiki/Standard_year.