Ads Are Not Displayed

Test ads are fine, but when I put the real ones they don't appear.
But the admob account is fine. It seems to me that the ads have been requested but 0 hits. Can you help me, please?

 

If the test ads work then it is something local to device, account, region, fill rate, or etc. You can check up with Admob to double check but usually this is the case

 

and what could I do?

 

Double check with admob that your account is being served ads. Most likely it is