The chart title often appears above the chart and is used to describe the data that’s being presented. You can add a completely new chart title or simply change the text of an existing one.
The axis titles describe for viewers the category of data that’s being represented. Without them, it can be difficult to accurately portray information.
Select the chart
Click the Chart Elements button.
Hover the mouse over the label options in the list to preview them on your chart before making your selection.
Select the Axis Titles check box.
A text box is added for both the vertical and horizontal axes.