Do you mean how to convert a number of days to years, eg:
How many years is 2000 days?
To convert, divide by the number of days in a year
The year is a tad under 365.25 days (365.242199 is a closer approximation), so divide by this.
⇒ 2000 ÷ 365.25 ≈ 5.48 years.
If you mean something else, please re-ask with more details.