Helen, thy beauty is to me Like those Nicèan barks of yore That gently, o'er a perfumed sea, The weary way-worn wanderer bore to his own native shore. (1-5)
The poem's first full stanza is all about setting up this central speaker-as-exile idea. Or at least, it sets up the notion of the speaker as being able to return from his lowly, banished state—thanks to the beauty of our girl, Helen.
On desperate seas long wont to roam, Thy hyacinth hair, thy classic face, Thy Naiad airs have brought me home (6-8)
A glimpse of something beautiful can remedy feelings of homelessness and exile. Helen's "hyacinth hair" and "classic face" carry the speaker back home. The presence of beauty is enough to get the speaker back to where he belongs.
To the glory that was Greece, And the grandeur that was Rome (9-10)
The speaker's return to Greece and Rome suggests that, prior to meeting Helen, he was exiled from history, or at least the grandeur that these great civilizations represent. In other words, Helen allows him to better identify with the accomplishments of these two extremely important ancient civilizations.
Ah! Psyche, from the regions which Are Holy Land! (14-15)
Psyche is from some "Holy Land," but she's not there right now because she's visiting the speaker. Is she not allowed back? Is she on vacation? She seems out of place, which is how the speaker felt earlier in the poem.