radio noise

Mac Catalina 10.14.4

Audacity 2.3.3
I am trying to get rid of radio noise to recover a voice file. I read the instructions and other answers to questions, I still don’t get it. How would I go about that?
Thank you

If the radio noise is varying in frequency-content, e.g., Audacity noise reduction will not be able to reduce it.

Catalina is 10.15. Mojave is 10.14.