So, a lot of these are basic Processing questions likely better served on the processing forums, and not specific to Syphon.
This tells Processing to import the Syphon library for Processing to use. The codeanticode part is because that Syphon library was written by https://github.com/codeanticode 🙂
PGraphics is a variable type, processing graphics, its the ‘canvas’ type that Processing uses in this case.
Id suggest you hit up the processing forum and docs to understand how to configure /customize your drawing! Good luck!