I'll only answer with an analogy. Visualize a cluster of magnetized particles on a hard disk platters. Billions of atoms linked with complicated quantum electromagnetic fields. A magnetic head goes over them. It fires electrical currents, that are sent a semi-conductor. That semi-conductor then starts doing computation, which is just electrons flowing from one part to another, from a semi-conductor to another. And then, another flow of electrons fired by a electron gun and hitting a screen, and they end up printing numbers.

You have that in your mind's eye ? Now, those numbers are the digits of Pi. According to my theory, the digits of Pi that appears on the screen are the same thing as some aspect of all those billions of Pi-less atoms in motion. Well, yes, and ? There is no dualism involved in that.

As for something being "green", we can detect "green" with webcams and computers. My Gimp as a "anti-red eye filter" that can not only detect a kind of red and even its shape, and remove it. Being green is a very physical property of light, or of matter that emits/absorbs light. There is even less dualism in that than in my Pi example, or in any other kind of file (text, pictures, sound, movie, ...) stored in a hard disk.