Calculating the current Age based on a date-of-birth column:
FLOOR(HOUR(TODAY()-[DOB])/365/24)&" yr "&
FLOOR(MOD((HOUR(TODAY()-[DOB])/24),365)*12/365) & " mo"
HOUR(TODAY()-[DOB]) returns the number of Hours in the duration
/365/24 converts hours to years, and
FLOOR gives the number of full years, dropping the decimal.
(HOUR(TODAY()-[DOB])/24) returns the number of days in the duration
MOD((...),365) finds the remainder in days, after removing the full-years
FLOOR(MOD(...)*12/365) converts those remaining days to months, dropping the decimal.
This could also be used to show other durations, such as a count down to a future date.