A walker goes into the woods and finds "good company," but the poem quickly makes that company strange. The trees, or whatever presences the speaker senses, are "absent as a drunk" and "present as an old sign." Both comparisons are odd and a little funny. A drunk can be physically there while his mind is elsewhere, and an old sign stays put, faded, still saying something though nobody reads it. So the woods feel companionable and distant at once.
Then comes the quiet turn. The speaker says one word, and the poem ends with "away home," as if that single word broke the spell. The poem doesn't say what the word was, and that gap is part of its charm. Judging by the lines, the speaker seems to value a wordless kind of togetherness, and speaking ends it. The mood is calm, gently humorous, and slightly wistful. It suggests that some closeness only lasts while we stay silent.