This horizontal bar chart ranks the 30 most populous countries in 2020, using population size along the x-axis and country names along the y-axis. The visualization loads CSV data from a GitHub repository via `d3.csv`, processes it with a custom row function, and sorts the entries in descending order. The chart is rendered as an SVG using `d3.select`, `scaleLinear`, and `scaleBand`, with axes generated through `axisBottom` and `axisLeft`. Bars are drawn with `selection.join('rect')` and are styled with a light green fill, while tick labels use a custom si-format prefix converter that replaces 'G' with 'B' for billions.