A heat map visualizes monthly rainfall totals in Liberia for 2021, using a vertical column of colored cells where darker shades represent higher precipitation values, with each cell labeled by its numeric amount and month. The p5.js sketch loads the data from a remote CSV file through the `loadTable` function in `preload`, then draws the map in `draw` using `createCanvas`, `fill`, and `rect` while mapping rainfall values to color intensities with `map` and `max`. The code also uses text functions to display month labels along the y-axis and a title at the top of the canvas.