The only problem with CIE XYZ is that it’s a remarkably inconvenient way of specifying color. Among other things, X, Y, and Z are abstractions and have no physical equivalent; there are no XYZ light sources. Also, practically speaking, what we want to do is specify color in terms of RGB for a particular monitor or CMYK for a specific printing press and paper.
This is where the notion of a color profile comes in. A color profile defines the conversion between a particular device’s colorants and XYZ. That is to say, the color profile for the BFD14½ G-Wizzy LCD display contains the data needed to convert RGB values intended for that display to the XYZ values that express how those RGB colors look on that display.