A color legend maps ordinal categories to hues, displaying two large circular swatches for "apple" and "lemon" against a white background. The `d3.scaleOrdinal` assigns red and yellow, while a custom `colorLegend` function binds the scale's domain to SVG groups. Circles and text labels are appended and updated via enter/merge/exit selections, with transform positions calculated from array index and a fixed height. The example demonstrates reusable D3 v5 code for building legends with dynamic scaling.