The Chorus effect makes a single instrument sound like multiple instruments. It works by mixing the original signal with two signals that are delayed and modulated by an LFO (low frequency oscillator).
Delay - The amount of time the signal is delayed.
LFO Rate - The speed the delay is modulated.
LFO Depth - The amount the delay is modulated.
Stereo Spread - The width of the stereo image. Negative numbers swap the left and right outputs.
Dry/Wet - The balance between the dry and wet signals.
This gives you a thicker sounding chorus then the Chorus/Flanger because it uses two modulated audio signals instead of one.
For a natural sound, the higher the LFO Rate, the lower the LFO Depth, and vice versa.
It also works good with the wet signal only (Delay = 0, Dry/Wet = 127).