Unless there is something going on under the hood that actually modulates these waves at some control rate faster than you can move one of the wave-forming dots around with your finger, there is nothing like Frequency Modulation driving this synthesizer.
What it is: a single waveform synthesizer that lets you customize the wave itself, in finger-dragging time. Useful if you like to noodle with this sort of thing, although the controls are imprecise at first: the dots are more like force fields than line connectors. Most of the waveforms will not simply be drawn from dot to dot. But that is a good thing, because it allows you to draw more interesting waves than would be possible with five sample points.
Not a bad toy, but not a new FM synthesizer either, so... *shrug*