To illustrate poetic devices I will choose one of my favorite short poems, "Nothing Gold Can Stay" by Robert Frost, because Frost uses many types of devices.

Nature's first green is gold,
Her hardest hue to hold.
Her early leaf's a flower;
But only so an hour.
Then leaf subsides to leaf.
So Eden sank to grief,
So dawn goes down to day.
Nothing gold can stay.

There are several devices that poets use.  The first one is figurative language.  Figurative language is the use devices where meaning is not literal, such as simile, metaphor, personification.  For example, when Frost says that "nothing gold can stay" he is metaphorically describing gold as a pure and innocent, and also using nature as a metaphor for life.  People are born innocent, and Frost is suggesting that it is impossible for us to stay that way.  Another interpretation is symbolic, that nothing good can last.  Other simple metaphors include comparing new leaves to flowers, because both are beautiful.

Another device used in this poem is allusion.  Allusion is when a poet refers to another work.  Biblical allusions are common in literature.  In this case, the line "the leaf subsides to leaf/So Eden sank to grief" is  Biblical allusion to the tempting and spoiling of Eden, and therefore the sin of all mankind.

Sound devices are also common in poetry.  This poem uses rhyme, in this case couplets.  This means that the poem is made up of pairs of rhyming lines such as gold/hold and flower/hour.  This gives the poem a song-like, musical quality.