The Excel DAYS function returns the number of days between two dates. With a start date in A1 and end date in B1, =DAYS(B1,A1) will return the days between the two dates.
Purpose: Get days between dates
Return value: A number representing days.
=DAYS (end_date, start_date)
With a start date in A1 and end date in A2,
=DAYS(A2,A1) Will return the same result as: =A2-A1