The name stands for "General Purpose Abstraction Layer". GPAL is a set of C++ classes which are used to represent any kind of data and to manipulate them. Thanks to SWIG, it is usable in many programming languages.
irrBuild generates native solution, Makefile and workspace for irrlicht library and its examples using Premake based build scripts. These scripts can also be used as build templates for cross platform irrlicht applications.