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.

We show you how to create a Histogram chart in Microsoft PowerPoint. A Histogram is a graphical representation that shows frequency data.

Insert different values and go back and view the line plot on your slide in PowerPoint. Close the Chart in the Excel window when you are satisfied with the result.

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