Using a hotspot is a smart way to structure the content of your presentation.
It helps to avoid your slides appearing too full and disorganized. Clicking on the hotspot makes all the content that you've attached appear. It is up to you if you want to add a textbox, images, videos, calculators and graphs. Try it yourself and make your slides look more professional.
Tip for working with a hotspot:
Uncheck the marked checkbox for disabling the hotspots to make changes to the widgets that are under the hotspots. (Note: Don't worry, you are not disabling hotspots in the presentation, merely hiding them to edit what is underneath.)
You are then able to make changes.
See also: Tip - using transparency for hotspots