Meaning: The sentence describes a cat resting in a seated position on the horizontal ledge at the bottom of a window.
Choice of Words: "Cat" is a noun that refers to a domesticated feline animal. "Sat" is a verb that means to rest in a seated position. "On" is a preposition that indicates position or location. "Window" is a noun that refers to an opening in a wall or roof that allows light and air to enter. "Sill" is a noun that refers to the horizontal ledge at the bottom of a window.