why does the title of the poem have quotation and a dash mark? and how does it relate to the content of the poem?

The title is an allusion to Shakespeare's Macbeth hence the quotations and the dash (signifying more lines after it). The Macbeth quote goes as so,

"Out, out, brief candle! Life's but a walking shadow, a poor player that struts and frets his hour upon the stage and then is heard no more. It is a tale told by an idiot, full of sound and fury, signifying nothing"

Similarly the boy's life is snuffed out in the poem with a similar commentary on human life.