A horizontal bar chart displays the populations of the ten most populous countries, with population values formatted in billions using a custom tick format that replaces 'G' with 'B'. The chart uses d3.scaleLinear and d3.scaleBand to map data from a CSV file, while d3.axisLeft and d3.axisBottom generate the axes. Custom axis styling removes domain lines and adds tick lines, with the x-axis label and chart title styled via CSS.