In Excel, you can use the Add Chart Element→ Legend command on the Design tab to add or remove a legend to a pivot chart. When you click this command button, Excel displays a menu of commands with each command corresponding to a location in which the chart legend can be placed. A chart legend simply identifies the data series plotted in your chart.
You can also choose the More Legend Options command, which is the last command on the Legend menu, to display the Format Legend pane. The Format Legend pane allows you to select a location for the legend and also to specify how Excel should draw the legend.
In Excel 2007 or Excel 2010, you use the Legend command on the Layout tab to add or remove a legend to a pivot chart and to customize a legend. Note that in Excel 2007 or Excel 2010, the More Legend Options command displays a Format Legend dialog box rather than a Format Legend pane.