This interview question is direct, and it's targeting your overall human resources knowledge. In your HR career, you may hear the term 'employee attrition rates' as an important metric. This means is that a company is losing staff due to natural reduction, including resignation, retirement, or relocation.
Attrition is the speed or rate at which something declines. Keep in mind; this term refers to natural reduction. Employee attrition rates would not include mass layoffs, for example. Show the interviewer that you understand what attrition means and the primary causes of employee attrition.