Kipling is making both an explicit and an implicit recommendation in this poem.
Explicitly, he is telling the United States to "take up the white man's burden." He is telling them that they should go out and do their duty since they are superior people. They need to go, take an empire, and try to help the people they conquer.
Implicitly, though, Kipling is telling Americans (and other imperial powers) that they need to be ready for what will happen to them. He is recommending that they prepare themselves psychologically for the burden that they are taking up. He is warning them of all the problems that they will face; the anger and the incompetence of the people they will try to rule. He is recommending that they should be stoic and firm in the face of the problems that empire will present to them.
Thus, there is both an explicit recommendation and an implicit recommendation in this poem.