A horizontal bar chart displays the 18 most populated countries in 2020, using UN population estimates. The chart customizes both axes: the y-axis removes tick lines and domain, while the x-axis formats population values in billions using D3's `format('.3s')` and adds a custom label. Bars are red rectangles on a blue background, with a title above. The visualization uses D3 v5 with `scaleLinear`, `scaleBand`, `axisLeft`, and `axisBottom` to render SVG elements.