If you have used Excel you probably have used charts, or at least seen people use them in a spreadsheet. They are nice because you can easily visualise data. So it is probably a good idea to have them, when needed, in your PowerPoint presentation.
The great thing is you can either copy a chart you have already created in Excel into PowerPoint, and if you want to link to Excel so that if the data is updated it updates on PowerPoint too. You can also create a chart right there in PowerPoint.
Here is this video I show you how to create a chart in PowerPoint and also copy one across from Excel. I also go over formatting and how to add elements like legends.