Here we use one color (Fill color) as the fill color on the line and a width (Width). In addition it is indicated how stippling be distributed, the number of pixels that will be filled with color and the number of pixels to appear between each filled color (Pattern). In this example, that therefore 30 pixels with color and then 10 pixels with no color, 30 pixels with color again and so on. Here one can only trial and error with different values until you find the stippling one wants.
Example on legend
Example on map