What is a country code and What's the code for louisiana ??

Since Louisiana is situated in the United States then it's country code is +1. When it comes to area codes it becomes a bit more complicated because the State is big and has 5 area codes: 225, 318, 337, 504, 985. If you face problems with area codes then go here https://areacodes.net/904 and check them. It's fast and easy.

Country code are only needed when you are calling another country from the U.S. If you are calling withing the United States all you need is an area code and the phone number.
Area codes for Louisiana are:
Alexandria area code 318; Baton Rouge area code 225; Bossier City area code 318 ...Houma area code 985; Kenner area code 504; Lafayette area code 337 ...