The indicator plots the Zigzag ("saw") using the High and Low prices.
The DRAW_ZIGZAG drawing style allow to draw sections using the values of two indicator buffers. It looks like DRAW_SECTION, but it allows to draw vertical sections inside one bar. The color, width and style of Zigzag lines changed randomly after N ticks. The N variable is defined as input parameter, it can be changed using the "Properties" window.
See also: The Drawing Styles in MQL5.