Looking for information

Hi everyone! If you’re in the US, happy belated thanksgiving!!

Like the title says, I’m just looking for information to educate myself better :) I’m a nurse (RN) who’s working part time at a pharmacy; I took a little break from nursing but have been applying for jobs again lately! I actually just started at the pharmacy not too long ago and the topic of denials and PA have come up, we learned NONE of this in nursing school so I am really confused, have been trying my best to relate it to stuff I know but idk 🤷🏻‍♀️ I honestly did a lot of research over the weekend but it just made me even more confused… I would ask one of the pharmacists but they’re so busy all the time I don’t want to bother them.