The visualization displays the annual number of data points from 1880 to 2015 as horizontal bars, with the x-axis representing the year and the y-axis showing the categorical years. It uses d3.scaleLinear for the x-axis, d3.scaleBand for the y-axis, and d3.axisLeft and d3.axisBottom to render the axes. The bars are appended as SVG rect elements with their widths proportional to the year values. The data is loaded from a CSV file using d3.csv.