The word "If" is repeated a total of thirteen times throughout the poem. Every time the word "If" is repeated, it is used to introduce a new condition. For example, the opening line of the first stanza begins, "If you can keep your head," the third line of the same stanza begins, "If you can trust yourself," and the fifth line of the same stanza begins, "If you can wait." This same pattern is repeated in the proceeding three stanzas of the poem, and, at the end of the final stanza, we discover that the result of meeting all of these conditions is that one will become "a Man." In other words, a man, according to the speaker, is somebody who, if we take just the conditions in the first stanza, is calm in difficult circumstances, is confident in his own abilities, and is patient. Other conditions elsewhere in the poem include the ability to think clearly, the ability to act decisively, and the fortitude to endure difficult circumstances.
The usual effect of repetition is to emphasize the meaning or connotations of the word or phrase that is repeated. In this instance, the repetition of the word "If" so many times throughout the poem emphasizes that being a man is not easy. One can only be a man, according to the speaker, if one can first meet a series of conditions. All of the conditions presented in Kipling's poem are conditions pertaining to one's character.