The visualization displays the Iris dataset, plotting sepal length against petal length, with species differentiated by distinct shapes provided through D3's `symbolsFill` and a custom shape legend. D3's `scaleLinear`, `scaleOrdinal`, and API methods like `axisLeft` and `axisBottom` construct the chart axes and markers. The SVG is generated dynamically, and the data is loaded asynchronously from a CSV file via `csvParse`, with numeric fields parsed after fetching.