We know from the title that the speaker of this poem is a black girl. She's singing, and we're going to guess that she's singing something like the blues.
She uses the refrain, "Way Down South in Dixie," so she's somewhere in the Deep South, maybe Louisiana or Georgia. But then we get these weird parentheses, which let us know that someone or something is breaking our speaker's heart. In other words, keep the Kleenex close.
We find out that her heart is breaking because her lover, who is also black, has been lynched. He's hanging from a tree that's in a crossroads, so people can see him as they pass.
The refrain repeats, and then we get an image of the brutality of the lover's death—he's been beaten up and is hanging high in the air. Our speaker is so upset by his death that she wonders, what's the use of praying to a white Jesus?
Then, in the last stanza, we return to the same first two lines as the first stanza. After we're reminded that the speaker's heart is broken, way down South, she give us the metaphor to end all metaphors. Love is a shadow—a naked one, on a gnarled and naked tree.