The first thing we notice about the title is that it's not in English. Ah, those months of sitting through Madame Brunot's French class have finally paid off: "Portrait d'une Femme" is French for "Portrait of a Woman." Even without Madame Brunot's class, you might have been able to figure this out, with "portrait" being the same word in both French and English, and "femme" sounding a lot like words we know to indicate women, such as "female" or "feminine."
So why is the title in French? What extra significance does this association with French give both the title and the overall poem?
Pound's motivation here is definitely worth considering, since "Portrait of a Woman," immediately recalls another English-language literary work, Henry James's novel The Portrait of a Lady, published three decades before Pound's poem. Not only was James a longtime hero to Pound, his novel also inspired two of Pound's closest literary allies, T.S. Eliot and William Carlos Williams, who both wrote poems entitled "Portrait of a Lady."
Pound wouldn't have known of Eliot or Williams's poems when he wrote "Portrait d'une Femme," but we might note that he's the only American in this group to translate James's title into a foreign language. This is especially strange considering the fact he deliberately places his "femme" in England ("London has swept about you this score years" (2)). Perhaps the French title helps broaden the poem's setting, so that we can see the woman within a more general European context. Or maybe it indicates that in a cosmopolitan city like London we can see evidence of many different cultural influences.
James's novel is a coming-of-age story about a young, inexperienced American girl who travels to England and Italy and undergoes a distinctly global education. Pound's title might refer to this kind of globalization – the sense that "it's a small world after all" – which was becoming more widespread in his time thanks to recent technological advances in travel. Think about the increase of railroads, the improvement of ships and ocean liners, and the invention of cars, all happening in the late 19th century.
The French speakers among us might also point out that the title uses the indefinite article "une" (equivalent to "a"), rather than the definite article "la" ("the"). Perhaps this poem is not a portrait of a specific woman, but of a broader type of woman – one that exists universally, in various places and various languages.