VoIP is a way to save money on voice calls. Typically it is used for computer-to-computer and computer-to-phone calls. Since many modern phones are computers in many ways, VoIP also could be used on such phones as an alternative solution for voice calls.
Just google VoIP and check one of the first articles from Wikipedia.

I have no clue how to take advantage of VoIP. Can anyone give me an example or a list of why VoIP is great? Is this a way to save money from the voice plan or something?

This isn't a joke, VoIP is something I never got into. Thanks.