I'll give you my 2 cents.
In fact, I still have a vague souvenir of having had questions like the OP, and then this got slowly brainwashed out of me, like by drinking Dyonisos' wine, but it still comes to me in my dreams
It's about the transition of a pre-scientific apprehension of things, with or without some mystical flavor to it, and the (erroneous) conception of science (as a kind of Revelation) that goes with it, and the bare bones actual science that you learn afterwards (if you decide to do so).
It might be very disappointing, but in fact, each time in science, especially in physics, when you ask what something "really is", you'll get two kind of answers:
- this is how we measure it / this is how we observe it / this is what it does
- this is the mathematical concept by which we define it in this theory
depending on whether you're experimentally or theoretically inclined.
You'll never hear, to your great frustration, that Charge is the yellow stuff that came out of the Right Ear of the God Coulombys when he made love to the Goddess Sparkina at the beginning of the world and permeated the universe or something.
What you'll find out is that people introduced the concept of "electrical charge" to explain a phenomenon which was electrostatic repulsion and attraction. They saw that you could associate a *number* to a piece of matter and that that number could be used, together with distance, to quantify the electrostatic repulsion. What that number stood for was not said. It was just the number that could be associated to matter to explain a phenomenon: electrostatic repulsion.
An arbitrary but clearly stated "calibration" was introduced to define the scale, or the unit, of that number.
Later it was found out that there were other phenomena, and that that *same* number turned up. From that point on, "charge", or the number we originally associated with a piece of matter to explain one phenomenon, namely, electrostatic repulsion, became a concept by itself, that was a "property" of matter, and that entered into several descriptions of several phenomena.
Several theories describe, on several levels of "microscopicity" and on several levels of sophistication, matter, and several of them use a mathematical quantity, namely a number, that they define as "electrical charge". It is used in circuit theory, it is used in electrostatics (Coulomb law), it is used in classical electromagnetics (Maxwell theory), it is used in quantum field theory... and although details can sometimes differ, it is grossly always about the same "stuff" we're talking.
So charge gets a kind of individual life of its own: it is clearly "something" that is physically meaningfull, as it enters the quantitative description of several different phenomena, and it enters several theories of physics in a kind of "unity".
But at no point, we say anything about what IS charge, except for all of this together: it is a number that is associated to matter and appears in the explanation of several phenomena, and it is a theoretical concept that is "robust" against the change in theoretical description level, so it must represent something with a strong physical meaning.
And that's it.
For some physical concepts, we can go further, because our biological senses have given us a primitive apprehension of it, a concept we already possessed since our early childhood. "Space" or "distance" is such a concept. "speed" is another one. But for charge, we don't have such a "pre-intellectual" primitive understanding, so we have to "build" one with the myriad of properties and theoretical constructs which differ in detail, but all point to a common physical "reality" of the concept at hand.
And that's the best we can do, contrary to what we (I ?) thought science would be teaching me when I didn't know any of it.
To "unlearn" or to "brainwash" yourself so that you can accept that physical concepts are nothing else but a cloud of properties and some persistent concepts in "nested" theories, or at least, that you won't know more than that about it, is an important conceptual step in becoming a physicist I'd say.