@freddie82 Yeah, watch as many videos as you can. From what I understand about shaders is they contain algorithms that calculate how light interacts with the object. So, when I was first learning about shaders, there were 3 ways light would interact: lambert, blinn, and phong shaders. A lambert is a very diffused surface; no highlights. So, something like flat or matte paint. Blinn has a soft highlight, something like the fake wood appearance on a cheap desk. Phong is a strong highlight, like a glass bottle. Now, shaders have gotten more complex and can do a lot of cool things.
According to Wikipedia, “…a shader is a type of computer program that was originally used for shading (the production of appropriate levels of light, darkness, and color within an image) but which now performs a variety of specialized functions in various fields of computer graphics special effects or does video post-processing unrelated to shading, or even functions unrelated to graphics at all.” So, at the base level, it’s a program that describes how something should look when rendered. Hope this helps, and feel free to ask any follow up questions.
