Excuse me, I participated in the recruitment of reserve cadres at KFC. After the interview, they called me and asked me to apply for a health certificate. What does this mean?

I have also applied for a job, but in Hangzhou, KFC requires a health certificate to indicate that you will be hired. After all, you are working in a restaurant. The so-called reserve cadres are actually not waiters. If you work for a long time and do well, you will be gradually trained and the company will conduct regular assessments. The salary is only about 1800 to 2500. But KFC has a good environment.