The phrase "high turnover" means a situation where many people leave a job or organization and are replaced by new employees frequently. Full definition
With high turnover rates in the retail industry, finding and securing the right talent is no easy task. (screen.careerbuilder.com)
One of the things to bear in mind is that dive shops can have relatively high turnover of staff — it is just that kind of industry! (tioman-scuba.com)
If the job keeps popping up in your search every few months, it could be an indication of high turnover in the position — which could indicate poor management. (topresume.com)