Well, I'll start by admitting I'm no artist or photographer. However:
Art is largely about seeing. You may object, after all, most people can see.
But it is different to do the seeing yourself, and to understand seeing so well that you know how to guide the eye of another onlooker through a picture, how to delight their eye, or surprise it.
I remember my father (an art major) telling me about an art class he took where one day he suddenly understood what the art professor was trying to convey. That professor was trying to teach them about dividing up the space of the picture. The visual notion "clicked" and from then on he did well in that class, where some other students never did. He had learned to speak a visual language that had been invisible to him up until that point.
Most visual concepts are like that.
It is one thing to see in the everyday sense. You know when your eyes present you with a beautiful scene. It is another to look at the scene and be able to diagnose it into visual components that cooperate and build up the beauty of the scene.
In my experience, new visual concepts sort of "pop", and suddenly become visible, where they were invisible before.
The point is, the more you can see, the more you can recognize when the image in your frame is put together in a way that will delight the eye.
Composition is an example of a visual concept. If you look at Raphael's paintings you can see that he likes to guide your eyes so they cycle through the paintings. His paintings of Mary with Jesus and John the baptist as toddlers have very prominent compositions and are great examples of the concept. Composition is also used in photography, as it is part of the visual language which can resonate with people, even if they can't describe why.
Rhythm is not just a musical concept, there is a visual notion of rhythm that plays a strong role in a lot of great images. It is also part of the visual language the eye uses and which can be used to move the onlooker. However, most onlookers, while delighted with the outcome, may not be able to say just why that outcome struck them beyond a statement that it was pretty, or they liked it, or it was breathtaking, possibly pointing out a few matters here or there that they really liked.
So it is about learning to see. Insofar as you can do that, you can improve your pictures dramatically over time. Or whatever artistic medium you choose to pursue.
I don't offer this as someone who claims to know much. I am more comfortable with a pencil than a camera and I am not an artist. But I can recognize when I have learned a visual concept and can, from that point on, see it's use in the works of many others more capable than myself. And once I can see it, I can start trying to incorporate it into my own images. But until I do, that is impossible.