"Properties doc for shaders?

I’m absolutely begginer in shaders. I’m trying to understand them. But in every tutorial people keep using “.color” “.position” etc. And I don’t know (and cannot find anywhere) what those properties are exactly. Where I can find the documentation of those “properties” like “.color” etc.

Actually if you’re really intresded i can recomend this book
it’s got any usefull information about shaders and is understandable written!