The poem begins with how we normally use language: as a tool. Say "chair" and someone knows what you mean, so they sit. Words name things and demand a response, and everyone understands the general category even if each person hears it a little differently. In everyday talk, the speaker says, words are simply a means to an end.
Then the poem turns. In poetry, words become ends in themselves, like a dance or the good china kept for special occasions. The speaker moves to a quiet evening scene, when the chores are put away and people share talk or a book. The mood softens into hush. Even the hedges and dozing birds seem to be listening.
By the end, talk has no job to do. It is "talk for talk," and the words drift like leaves, still alive. The feeling is calm, appreciative, and a little tender, a celebration of conversation enjoyed purely for its own sake.