It's a drawing of a cylinder that is divided into three short cylinders stacked directly on top of each other. It's like the shape of a three layer cake. There is a plus sign inside of a circle that is placed over the bottom right of the cylinder to indicate, "add database."
Related to Add Database Icon
Related icons are the icons with matching tags, as well as all data icons. All icons are in the same flat style. You can either download free PNG icons or buy SVG vectors