To see the sketch in action, please allow the website to access your (web)camera.
The sketch you should see running above accesses your (web)camera and uses the image to create a nice visualization. In this case the sketch is added as a file to my website. That means that if I ever want to make changes to the behavior of the sketch, I would need to upload a new version. In a later example I will embed a sketch.
If you want to give P5JS a go yourself, the live editor with this example can be found here: https://editor.p5js.org/corvanessen/sketches/niKGLH2G1