I'm planning to buy one but I'm quite confuse with this feature. Will i be able to store my effect on one of those presets? what does it actually do?...thanks guys in advance..
You can't store an effect or anything like that. It just allows you to use effects after the pedal's built in distortion, and have it sent out with the DI.

Some effects--mostly modulation and delay--usually go best after your gain settings, and the effect loop lets you put them there instead of in front of the pedal.

If you just put them after the pedal, you wouldn't be able to send them out on the DI.