The XY Model is a model used in Condensed Matter Physics to better understand the physics of atoms on a 2d lattice. Each atom has a spin property which can point in any direction on the plane.
The first three sliders are used to control the Temperature, the Interaction Strength and the External Magnetic Field. The fourth is used to adjust the color of the visualization. The color and direction of the lines illustrate the direction of the electron's spin.
Some code referenced from Joshuahh on Github