In just two short lines, this haiku-like poem pictures a wedding held somewhere remote and rural, as the title "Backwoods wedding" suggests. The first line, "day of new vows," tells us what is happening: two people are promising themselves to each other, and the word "new" gives the moment a feeling of fresh beginnings.
The second line is where the poem opens up. "All the rough hill sang" gives the landscape a voice. The word "rough" matters here. It suggests a hillside that is uneven, wild, maybe a little hard to live on, and yet it sings. We can read this literally, as birdsong, wind, or insects filling the air, or more loosely, as the speaker feeling that the whole place is celebrating along with the couple.
The mood is joyful but unpolished. There is no grand church or formal music, just a rugged setting that seems to bless the occasion in its own way. The speaker comes across as moved and quietly delighted.