Perception: our sensory experience of the world.
Developing your perception as a photographer takes practice. I would say it is a life-long practice that you will engage every time you photograph. For a photographer perception is how we see the difference between an interesting sight in the world and an interesting subject for an image.
Close your eyes and snap a photo. The result will probably tick the failure box on some level. You haven't engaged with the subject. It doesn't matter if the subject is a tree, building or person. To grow that basic photo into something beyond a surface level image you need to see beyond the basic.
I see a tree and while it may be a stunning specimen of a tree, I need to see what is it that makes it deserving of a photo or will make it something the viewer will stop and stare at. Is it the bark? Could it be the pattern of the leaves or needles? Whatever it is I need to perceive what that tree has to offer that will make a meaningful image. And then I can begin to develop a plan to bring that tree to life as an image.
Not everything you see in your chosen photographic genre will be worthy of a photograph. Your perception will slowly become aware of what stands out. What makes you stop and look twice today you might not have noticed last year.
Your perception develops as you study and learn about light, shadows, line, and weather. You start to see how all of this affects your chosen subject. You start to engage with the subject. and then you start to realize that rarely, if ever will everything you need for a perfect photo come together perfectly. You start to work the scene because your perception has developed and you are instinctively engaging with the scene.
Before you snap that photo of a pretty subject, stop an take a deep look around. What will make your photo different from the thousand other photos of the same scene or subject?