This code starts out with a point in the bottom middle of the screen. It then moves the point up a little bit, and randomly a little bit to the left or right. It also randomly changes the color to a shade of green. It repeats that process every frame, and the effect looks like a vine growing up the screen. If you leave it running long enough, you get something like this:
This is a companion discussion topic for the original entry at https://happycoding.io/examples/processing/animation/vine