Currently, the chart functionality will only show the default X & & axis names for the Grouping, or the field values when stacking fields. It would be beneficial to be able to customize what appears in the legend, as well as the X & Y axis names.
For example, if you have a chart that shows the number of projects (X axis) completed by month during a specific year (Y axis) with field from a custom form with a Yes or No value stacked in the results, it is not clear what the additional grouping is.