In this poem, Kipling's speaker outlines for his son the behaviors and attitudes it takes to become a man—in this case, a gentleman in British society. It is good to keep in mind, however, a concept from the Italian Renaissance that lies behind the speaker's advice. This is sprezzatura, which means projecting a nonchalance or effortlessness in everything one does, and in that way, making difficult tasks look easy and natural.

In the first stanza of the poem, the speaker advises his son to cultivate keeping his cool or keeping chill when others around him are losing it. He also advises his son not to repay low behavior with low behavior—don't respond to lies with lies or hate with hate. In other words, to use current parlance, when others go low, you should go high. He advises sprezzatura, too, when he states his son should make this all look natural and effortless:

yet don’t look too good, nor talk too wise

In the second stanza, the speaker turns to advising his son to develop self control, as well as an ability to hear the truth and avoid flattery and have grace under pressure. No matter what happens, his son should respond to it with cool equanimity, treating triumph and disaster with the same ease. If his life's work is broken, he should simply quietly and graciously pick up the pieces and rebuild, as if it is costing him no effort:

watch the things you gave your life to, broken,

And stoop and build ’em up with worn-out tools

The poem is a father defining for his son the qualities of a good man.  he is setting the parameters or boundaries for his son and giving him a goal to achieve.  The poem deals with life's challenges and hw to deal with them.

Stanza one deals with being confident about the decisions you make and taking responsibility for those decisions.  If others, who cannot take that responsibility for themselves, react negatively, you will be patient with them and not reduce yourself to their level by telling lies or dealing in hate.  However, don't ever think you are above anyone else.

Stanza two states that it is good to dream, but don't let your dreams control your life. It is good to think, but those thoughts need to be put into action. You will experience both triumph and disaster in your life.  Don't take them too seriously because they are not the substance of life, they are the extremes.  If you hear things you said misused or things you have done destroyed, you need to be able to pick yourself up and rebuild them with everything you have left in you.

Stanza three counsels not to be afraid to take risks and possible lose everything.  If you do lose everything, don't talk about it, just start all over again at the beginning.  When you have pushed yourself to your limit and you are tired and exhausted, use your mind and your will to move yourself forward.  Push through it.

Stanza four deals with a person's reaction to others.  You need to be able to talk to a large group of people and not let them influence your belief in what is right, wrong, moral, or immoral.  You need to be able to walk beside men of power and influence and yet not lose touch with the common man and his needs.  You need to know yourself and your beliefs so well that neither your friends nor your enemies can hurt you because you know who you are and what you stand for.  People can depend on you, but don't let others become too dependent on you.  It is important that you live every single minute of every single day of your life to the fullest.  If you do these things, then the world is yours, and you will be a good man.