If you’re getting into shaders in Godot, The Godot Shaders Bible is a solid place to start. It explains the basics without assuming prior experience, then slowly builds into more advanced topics. 

The free sample gives a small look at some of these concepts, while the full book goes much deeper into them.

For example, one of the things the sample explains is what a shader actually does inside Godot.

In simple terms, shaders are small programs that run on the GPU and control how objects are drawn on screen, using things like position, color, textures, and lighting data.

In Godot, shader files are usually split into two main parts: the  vertex() function,  which changes the geometry before it gets rendered, and the  fragment() function, which controls how the final surface looks on screen.

Before the final image appears on screen, the mesh data goes through multiple stages inside the render pipeline, where things like vertices, UVs, normals, lighting, and screen space transformations are processed step by step. The vertex() and the fragment() functions are some of the most important parts of this pipeline.

If you want to learn more, the book goes deeper into this. If you don’t feel sure yet about it, the free sample gives you an idea of how it is.