Getting to know the Python Console
The most direct way to interact with the QGIS API (short for Application Programming Interface) is through the Python Console, which can be opened by going to Plugins | Python Console. As you can see in the following screenshot, the Python Console is displayed within a new panel below the map:
Our access point for interaction with the application, project, and data is the
iface object. To get a list of all the functions available for
help(iface). Alternatively, this information is available online in the API documentation at http://qgis.org/api/classQgisInterface.html.