There are a huge assortment of brushes in Sketchbook, some pressure-sensitive, others with textures, glow brushes, splatter, and much more.
Sketchbook "brushes" include not only actual brushes, but also erasers, markers, pens, and pencils.
All versions of Sketchbook and Sketchbook Pro come with hundreds of brushes by default, you can find them in the Brush Palette along the left side of the screen. If you have a smaller handheld device (ie: phone), your brushes will be in the Brushes menu 
.
When editing brushes, use Brush Properties, the Brush Puck, or Double Puck, or Brush Property sliders found along the side of the Brush Palette.
More brush topics:
