In order to give you some context for better understanding this very short poem's central metaphor, it is important to note that it was published within a longer volume of linked jazz-inspired poems called Montage of a Dream Deferred. Hughes considered the work a single book-length poem of jazz-inspired impressions of the Harlem neighborhood of Manhattan where he was living and writing in the years after World War II.
A montage is a juxtaposition of fragmentary components ordered to create a coherent meaning, and many of the other poems emulate the rhythm and textures of African-American music. Hughes suggests through the title that the collection of sketches and riffs on contemporary Black life in Harlem has as its ultimate subject the notion of the "dream deferred," and this poem serves as an introduction of that recurring theme.
As a national mecca of the fruits of African American culture in the first half of the twentieth century, like music, literature, politics and art, Harlem was an epicenter for the collective aspirations of Black America. Yet the fabled neighborhood also contained the same poverty, oppression, and disenfranchisement that Hughes would have known from his native Missouri and its Jim Crow traditions in line with the former Confederacy.
Far from being a promised land, slick, soulful, and gritty Harlem is also a place that robs, cheat, kills and exploits, breaking hearts and crushing dreams. There, one encounters the pinnacle of American success and establishment for those who pursued their dreams undauntedly. But the dream of many is deferred—passed over or put off—because the consequences of a marginalized existence render them defeated, devoid of confidence and courage, or worse. The various images of rupture and decay in the poem suggest that the costs of not pursuing a free and authentic existence despite the structural obstacles is spiritual death.