The x-axis represents bins. So if you have a continuous variable like age which has values from 0-100 then you can create bins like 0-10, 10-20 and so on (and here bin size = 10). You can change the bin size to analyze the distribution of the data. X-axis has a numerical (quantitative) variable. | The x-axis represents distinct categories from your data. The variable on the x-axis is usually qualitative |