The primary translation for _retention_ is indeed , but this word is not used with humans. Better words used in the human resource or marketing field would be ()(), (), , etc. A katakana word is also used in this sense.
Turnover is // when you want a technical term. is also common although this sounds less formal/technical.
> Company X's high turnover rate could imply they have a problem with employee retention.
> X
Casually, you can say: X