where should we go in palermo , we have 3 full days
This sums up the top things to see:
https://www.thecrazytourist.com/15-best-things-palermo-italy/
I highly recommend that you look at a guidebook for Sicily, Palermo in particular. Make sure you visit Monreale, Cappella Palatina, the Palermo Cathedral, Teatro Massimo, Norman Palace, street markets, etc..
As you see, you are getting basically the same advice each time you ask the same question. Have you looked at the answers on your other posts?
Hmm... Maybe the OP can't find their old posts?
Just click on My Account -> Travel Forum -> My History -> View All
I'm guessing that's why they keep asking the same question.