Chapter 1, Where Do I Start?, covers the installation of QGIS 3.4, major changes since QGIS 2.x, UI, and getting help.
Chapter 2, Data Creation and Editing, covers data formats, loading data, interacting with it, and vector and raster data.
Chapter 3, Visualizing Data, explains how to interactively style vector and raster GIS data.
Chapter 4, Creating Great Maps, covers the labeling of data, creating maps, and map outputs.
Chapter 5, Spatial Analysis, explains the Processing Toolbox, spatial analysis of vector and raster data, batch processing, and modeling.
Chapter 6, Extending QGIS with Python, covers actions, the Python console, plugins, and 3D applications.