To make a chart easier to understand, you can add chart title and axis titles, to any type of chart. Axis titles are typically available for all axes that can be displayed in a chart, including depth (series) axes in 3-D charts. Some chart types (such as radar charts) have axes, but they cannot display axis titles. You can’t add axis titles to charts that don’t have axes (like pie or doughnut charts).

Add a chart title

1. In the chart, select the "Chart Title" box and type in a title.
2. Select the + sign to the top-right of the chart.
3. Select the arrow next to Chart Title.
4. Select Centered Overlay to lay the title over the chart, or More Options for additional choices.
5. Right-click the chart title to format it with options like Fill or Outline.

Remove a chart title

1. Click on the chart.
2. Select the + sign to the top-right of the chart.
3. Uncheck the checkbox next to Chart Title.

Learn more: https://support.microsoft.com/en-us/office/create-a-chart-from-start-to-finish-0baf399e-dd61-4e18-8a73-b3fd5d5680c2