Year

A year is how long it takes for a planet to perform a complete revolution around their star.

For Earth, there are ~365.2421891 days in a year, or 365 days, 5 hours, 48 minutes, 45 seconds, and 138 milliseconds.

There are 12 months in a year.

There are, on average, 52.1775 weeks in a year.

Due to there not being an integer number of days within a year, the amount of days used in a year fluctuates between 365 and 366. Those are both integer values, which is why we don't get offset by ~6 hours each year. Earth currently follows the Gregorian Calendar, where if the year number is a multiple of 4, but not a multiple of 100 unless it's a multiple of 400, then the year is 366 days long. If that condition is not met, then the year is 365 days long.

Earth's orbit around the sun is not decaying due to the Earth being so massive and the Earth moving through a vacuum. A year will remain the same until the sun begins to die.