The toolbar in Sketch contains all the tools you need to create your masterpiece. The first set of tools in the default toolbar are for adding new layers; shapes, images, symbols and more.
The group and ungroup are for keeping your document organised. The next few sections are for editing layers; rotating, transforming, combining layers using Boolean Operations and moving layers backwards/forwards in the layer list.
The Export button (the last icon in the toolbar) will let you export your drawing to one or multiple bitmap or vector-based files.
Unlike many other drawing apps, Sketch does not have a toolbox with the common tools in there, instead they are in the toolbar. Additional tools and shortcuts can be added to the toolbar by right-clicking it and choosing “Customize Toolbar…”.