BBPG means Bobby Bolton's PolyGlot (Fork), which of course is a fork of Draque Thomson's PolyGlot. It is a conlang construction toolkit.
For full user documentation, see: http://draquet.github.io/PolyGlot/readme.html or the readme file included in the docs section of this project.
Instructions for building this project can be found in docs/readme_developers.txt.