Property list files (.pfiles) store serialized objects and are often used to store a user’s settings. They are also used to store information about bundles and applications in OSX and recently iOS.
Danilo Campos wrote some time ago some background information and provided his source and blogged about the subject. Better than that however, he provided an OSX binary to download if you want to get going straight away.
This little application makes it easy to format and process your source data in a familiar environment like Excel and then convert ready to use in your application.
EDIT: It seems Danilo has taken his blog offline, and also this binary. I suggest you now use this online tool: https://wtools.io/convert-csv-to-plist