Visual Studio Solution Explorer/Navigator Icons Meaning

If you mean the "Source Control Item Status" icons that appear next to files in the tree view.

See http://msdn.microsoft.com/en-us/library/ms181372(v=vs.80).aspx

Here's a list for the Solution Explorer/Class View/Object Browser icons : https://docs.microsoft.com/visualstudio/ide/class-view-and-object-browser-icons (I know that this is a 7 year old question but that's what I came here looking for... not the SCC icons)

I also have not found a comprehensive list of the icons, but can at least report that that the "no entry" icon (red circle with a horizontal white bar) means that the file is not included in the project.

I've hit the strange case where the Properties Window says Included In Project True, but the Solution Explorer shows, correctly, that the file was not included in the project. (Moral: Trust the icon.) The fix was, in the Properties window, change Included In Project to False, and then back to True.