I don't think it is rigidly laid down like a law, unit or other definition you have to learn. It just means what it suggests. Particularly contrasted to 'thermodynamically favoured'. E.g. given reactants often produce more than one product. One product might be more stable than another, i.e. thermodynamically favoured, but the path to another might in given conditions be faster so that is what you could get more of and you would call that being kinetically favoured.