Is Kipling saying that nations should or should not practice imperialism? And what will the CAPTIVES think of the White Man?

I am guessing that you mean "The White Man's Burden" which seemed to most to be a poem supporting the practice of imperialism as it had been practiced by the British Empire. The phrase "The White Man's Burden" seemed filled with racial innuendo and was, in a way a very negative way of looking at how a country might build an empire.