in simple words... job description specifies what is your responsibility and day -to - day duties while you hold a specific post in the company...
out of this daily responsibilities and duties few can be measured or quantified ,,, this is known as the key result areas, which denotes the accountability of the post towards the organizational goals. let me cite one example..
I am in room maintenance..ie , my job is to maintain a room..
now |job descrptions may be ..
1. Brooming atleast thrice in a day
2. changing the sofa , furniture covers
3. sweeping the floors twice in a day
etc....
now the KRAs will be
1.dusting management
a, broom the floors 3ce in a day ----ensuring 0% dust level.
b. Use brooms of 3 standard sizes to reach the inaccessible areas--- adherence to 100% quality standard...
2.Floor management
Sweep the floor at equal interval, with proper disinfectants
a. Maintain timeliness---- Sweep hourly/daily/weekly
b. ensure whole floor coverage--0-100% accuracy