To animate a line graph in PowerPoint, you need to open the slide, draw the Graph add the labels and then animate the graph as explained here.

How do I add data labels to Sunburst chart? When you create a Sunburst Chart in PowerPoint, the labels will add automatically to the chart; if there are no labels in the chart, you can right-click ...

How to Make Graphs to Put Into PowerPoint. Microsoft PowerPoint enables you to create presentations and slide shows. While a wide variety of text-, image- and object-editing features are available ...

Start the PowerPoint application and use the "File" menu to open the presentation containing the graph to which you wish to add the callout.