This is a vague question.
Shader processors on a GPU are the individual computation cores. There can be hundreds or thousands built into modern video cards.
You might also be talking about shader mods available for a wide array of games. SEUS for Minecraft, ENB for Skyrim, or ReShade are are software that latch on to a game's graphics system and offer special graphics enhancements or modifications. The effects range from modified color and saturation all the way to overhauled graphics features like improved lighting.
I hope I was able to help with your question.