Python is a powerful object oriented scripting language. You can find out more about the language itself on the Python website at http://www.python.org/.
KDE applications developed using Python use two important pieces of software, PyQt and PyKDE. PyQt provides Python support for the Qt library which KDE is built on. PyQt can be obtained at http://www.riverbankcomputing.co.uk/software/pyqt/ . Riverbank Computing has a lot of good documentation about how to use PyQt to create pure Qt applications. If you are new to KDE / Python development, then learning how to use PyQt is the best first step.
You can obtain PyKDE4 from KDE's svn:
It's also available via http://websvn.kde.org/trunk/KDE/kdebindings/python/pykde4/.
|The book Rapid GUI Programming with Python and Qt is available and covers Qt 4 programming with Python.|
PyKDE builds on top of PyQt and KDE's libraries and adds support for the extra libraries and features in KDE.