QGIS has a powerful programming interface that allows you to extend the core functionality of the software as well as write scripts to automate your tasks. QGIS supports the popular Python scripting language. Even if you are a beginner, learning a little bit of Python and QGIS programming interface will allow you to be much more productive in your work.
Unlike many introductions to Python, this one does not start with an installation and setup guide. Why? Because if you have installed QGIS, you already have a working installation of Python on your system. All you need to get started is to launch QGIS and open the Python console (Plugins | Python console).