A horizontal bar chart displays populations for the top ten countries from the UN Population 2019 dataset, loaded via d3.csv. The React app uses d3.scaleBand for categorical y-axes and d3.scaleLinear for quantitative x-axes, rendering SVG rectangles through custom AxisBottom, AxisLeft, and Marks components. React hooks manage asynchronous data fetching, while D3 v5 and v7 are both loaded in the HTML.