At times, you may like to add some indicator which can indicate the anomalies found on the chart or you may want to take the user's attention on a value of the data point; in such cases, you can use the shapes. The shapes can be dragged and dropped from the shape library available on right-hand side options. Depending on the need, you can choose any one or more shapes and place them on slide. Have a look at the following image to understand the context:

The sample use case is shown in the following image: