Wave Candy is a stock FX plugin in FL Studio, it is an audio analyzer with different types of visuals. I use the oscilloscope in this video to show you how you can use this plugin to get a basic comprehension of how synthesis works. Many newer synths these days have visual feedback but many synths still have limited visual feedback. If you use such a synth, then Wave Candy can be a useful tool if you are unfamiliar with how synthesis works.