Neruda isn't hiding any secrets in his title—the poem actually is an ode to a suit. Now, an ode is a poetic form of praise or appreciation, originating all the way back to ancient Greece. You may have read an ode or two already; Romantic poets like Keats and Shelley were big fans of 'em.
But we are betting you never read an ode to a suit, or a pair of socks before stumbling onto Neruda. And that's just the way he likes it. Neruda wanted to invest the world of everyday things with poetic importance. It's not just a nightingale or the west wind that deserves our praise and attention. This title tells us that Neruda's up to a different program. Everything is fair game for his poetic attention, even the suit on his back, er chair—you get the idea.