A child points at something. An adult says a word. The word becomes the thing. Tree. Dog. Stove. Hot. No. Good boy. Bad boy. The child stops seeing the world directly and starts seeing it through the categories the adults handed over.
K saw language as the original conditioning. Before religion. Before politics. Before any belief. There was the act of giving the child words for things, and the words themselves selected what would be visible to that child for the rest of their life. The categories built into your language built the borders of your perception.
Once a thing has a name, the name becomes the thing. You don't see a stranger. You see "a guy." You don't see the breath leaving someone's body. You see "a sigh." You don't see the moment between sleep and waking. You might not even register that there's something there to see, because no word in your language carved it out.
Try to describe a smell. The vocabulary runs out fast. You're left pointing at other smells, comparing. Smells like rain. Smells like grandpa's house. Smell is a sense your language never carved territory for. When you reach for it you find very little to grip. Now imagine that for entire dimensions of human experience for which your language gave you no words. Those dimensions are there. You just don't have hands.
Every act of looking is filtered by the language that taught you what to look at. You're not seeing the world. You're seeing the small slice of it your vocabulary has names for.