This feature allows you to create an effect to simulate printing in full colors on wood (if you make wood engraving instead, look here).
How it works
When you create a Printing Method, you enable the Print on Wood in Full Colors feature in the Effect section. You set an effect to simulate printing on your wooden product and the design gets that effect.
Zakeke provides you with pre-made effects that you can edit if you're not happy with the final result. In particular, an effect is composed of a blend mode and a level of opacity.
On the right, you can see how the effect would work on your customizer. By default, you see it on a wooden board but you can change the image and upload the image of your own product. If you check See without effect you can see the original colored image/text.