The symbols in this poem are the minstrel boy's wild harp, his father's sword, and the foeman's chain. His father's sword stands for the freedom his forebears have fought for, which he still believes in and is willing to die for--and has. Even if he has to stand alone, he will stand ("One sword at least thy rights shall guard"). The boy's "wild harp" symbolizes the songs of freedom, the freedom to sing them, and hope for the future. "Land of song!" is about a free nation who sings about hope and freedom. He takes his harp with him to battle--to remind his compatriots through song what they're fighting for. He destroys the harp as he dies, because it stands for (to him) freedom ("Thy songs were made for the pure and free, / They shall never sound in slavery"). Finally, we have the chains he fights against, which symbolize slavery. This is a typical symbol of slavery, to the extent that it is a common metonymy (a figure of speech in which a concept is referred to by a symbol of that concept, such as "the crown" being metonymy for "the king").