A D3.js animation constructs a smiling face from SVG shapes and then animates its eyebrows. The face is drawn using circles for the eyes and head, rectangles for the eyebrows, and a path for the mouth, created with the `arc` shape generator. Eyebrow movement occurs through chained `transition().duration()` calls on the group’s `transform` attribute, shifting it vertically. The code uses D3 v5 selection, attributes, and the `arc` API, rendering all elements as SVG within a 960 by 500 canvas.