Pana it is a venezuelan word that means buddy, pal etc. it is short for panaderia witch means bakery.
After the world war 2 lots of italian, spanish, portoguese and some
french moved to Venezuela. As a business lot of them opened
french/portuguese type bakeries (panaderias) where
people besides buying bread they could sit and have coffee, eat
french pastries, etc. People would hang in the bakeries so, in the 1950's friends hanging around bakeries would say hi by saying, Que paso panaderia! (What's up buddy).
Later in the 1960's and
70's the new generation started cutting the word down to pana so instead of Que paso panaderia! They would say Que paso pana!
And then in the lates 70's and early 1980's thanks to the big soapopera venezuelan business witch exported so many crappy soapoperas to latin
american countries words like pana, chamo, burda, malandro started being used by most of the latinamerican countries.