The doctrine that nothing exists except matter and its movements and modification.
This comes up every few days here.
This narrow definition of the term "Materialism" is clearly out of date and not useful anymore. It is trivially clear that there exists more than "just" matter. As far as we know today, the universe is made from 17 particles and 4 forces.
The latter contain the electromagnetic force, which (together with "movement and modification") what gives rise to the "information content", if you will, of our brain (if you subscribe to the physicalist viewpoint). As a physicalist, you would say that this is all there is to it - we cannot yet explain how it works, but we assume that however all the higher functionality of conscience etc. are "implemented" by nature, it is based, eventually, on said 17 particles and 4 forces. Only a rather small subset of those 17 + 4 make up actual everyday matter.
If and when we detect more, or come up with better theories, that will be adjusted of course, as it has been in the past.
So as a physicalist, you are not only concerned with matter, but at the very least with electric charge, and very importantly also with how said matter is connected (i.e., things like neurons channeling the electric or chemical energy content floating around in our brains). Speaking of chemistry: the chemical processes running within our bodies certainly do exist by any definition, and they are absolutely a form of information storage and processing (just think of all the hormones and uncounted other chemicals we know that float around, not to speak of the neurotransmitters in our brain that are themselves subject to other chemicals inhibiting or exciting them).
Same as there is a definite physical difference between a powered and unpowered computer. Nobody would say that as soon as you plug a computer in and flip the switch, there exists something totally new and un-physical - no, the working computer is just as purely physical as the unpowered one.
The term you're (maybe?) looking for is Physicalism. To quote from that page:
In philosophy, physicalism is the view that "everything is physical", that there is "nothing over and above" the physical, [...]. It is opposed to idealism, according to which the world arises from mind. [...] unlike "two-substance" (mind–body dualism) or "many-substance" (pluralism) views.
So to answer your question: a physicalist believes that all phenomena of our brain (including consciousness) are purely physical. It is then easy to suggest that the action of reading a statement, understanding a statement, or pondering on a statement, would be represented within our brain in some form or fashion (i.e., as some kind of permanent or temporary circuitry expressed by a theoretically measurable set of neurons, their interconnections and electrochemical state, together with complex calculation processes chugging happily along).
Similarly as everything stored on a computer can eventually be traced back to a bunch of electromagnetic charges within its storage (be it permanently on a hard disk or temporarily in RAM). The storage "format" within there will have nothing whatsoever in common with the object it talks about, but there will be some kind of mapping that gives meaning to it. And this mapping does exist somewhere (for example, mapping a number between 0 and 255 to a letter - this mapping is given in "code pages"; storing a text in a computer only makes sense if you also specify, usually implicitly, which mapping or code page you mean. Storing the number 65 for "A" in the computer "looks" nothing like the letter "A".). All of this is purely physical, there is nothing unphysical about it.
To meander back to the brain - a physicalist would assert that the brain is fundamentally the same, just of course technically completely different and unfathomably more complex, and totally opaque to us today. But still, just physics down to (a rather small subset of) the very fundamental 17 particles and 4 forces.
