If you're a title, you have a pretty simple job: introduce the poem to the reader.
Sometimes, those introductions are super-helpful. Without them, you would have little to no idea what the poem is actually on about. "The Death of the Ball Turret Gunner" is one example of that. If the title didn't tell you that it was about a World War II airplane gunner, you wouldn't know that "hunched in its belly" refers to being stuck in a plane.
Sometimes, though, they're totally useless, as in the case of a poem like "Sestina." In this case, the title tells us that this poem is a… sestina. Great—thanks for the tip.
This title, "Home-Thoughts, from Abroad," falls somewhere in the middle of these two kinds of titles. It's not totally worthless, because it summarizes the main elements of the poem that follows. Element 1: the speaker of the poem has some thoughts—wait for it—about his home. Element 2: the speaker has these thoughts while he is—say it with us—abroad. So, the title lets us know what to expect in the poem ahead.
At the same time, we could probably have figured that out for ourselves, even if the poem was called "Untitled." After all, the speaker isn't trying to hide behind a lot of obscure allusions or ambiguity here.
At the end of the day, the only remarkable thing about this title is the word "thoughts." After all, the whole poem is an exercise in imagination. The speaker is remembering—in vivid detail—what it's like to enjoy an English spring. On that level, that aspect makes the poem more than just an ode to England or a lament of being homesick. It's a celebration of the power of the mind to—figuratively, if not literally—transport us to the places we'd like to be.
By that token, the title announces that the best vehicle when it comes to travel isn't a bus or a plane. It's that little thought-producing gray matter that you keep between your ears.