A horizontal bar chart displays the top 10 most populous countries for 2019, with country names on the y-axis and population counts on the x-axis. The React component loads CSV data via `d3.csv`, then renders SVG marks using `scaleBand` and `scaleLinear` for positioning. Tick marks and axis labels are generated manually from the scales, while bars are drawn as `<rect>` elements with widths proportional to population values.