The valorisation or valorization of capital is a theoretical concept created by Karl Marx in his critique of political economy. The German original term is "Verwertung" (specifically Kapitalverwertung) but this is difficult to translate, and often wrongly rendered as "realisation of capital", "creation of surplus-value" or "self-expansion of capital" or "increase in value".
In German language, the general meaning of "Verwertung" is the use or application of something (an object, process or activity) so that it makes money, or generates value, with the connotation that the thing validates itself and proves its worth when it results in earnings, a yield. Thus, something is "valorized" if it has yielded its value. Similarly, Marx's specific concept refers both to the process whereby a capital value is conferred or bestowed on something, and to the increase in the value of a capital asset.
In modern translations of Marx's economic writings, the term valorisation (as in French) is preferred because it is recognized that it denotes a highly specific economic concept, i.e. a term with a technical meaning.