Understand
To understand is to stand among or within something, deriving from the Latin inter "between, among.," Greek entera "intestines." Internalize the poem. Read it out loud many times until the words become part of your muscle memory. Consider and clearly mark the TONE in the poem. Map the tone shifts throughout, from stanza to stanza, line to line, word to word. See what changes in the meaning when you say it aloud, using different intonations and inflections.
True understanding goes beyond knowledge or memorization, and comes from truly inhabiting the poem. Your understanding is also made up of misunderstandings and will continue to change as your relationship with the poem and with language and poetry in general evolve.