Hue refers to the attribute of a colour that allows us to distinguish it from others on the colourspectrum, and it is a fundamental concept in colour theory.
Different colour models define hue in slightly different ways and associate it with different families of terms, so it is best to associate it with a specific colour model to avoid confusion.
For example:
The RGB colour model works in practice by asking three questions of any colour: how red is it (R), how green is it (G), and how blue is it (B).
The HSB color model defines a colour by its hue (H), measured in terms of an angle between 0° and 259° on a colour wheel, and then determines its saturation (S) and brightness (B).