The title sounds like a sign nailed to a fence, and the poem reads like the world answering it. In the first stanza, the walls seem to "lease" the view of a place, as if even looking has become something you rent or are granted by permission. Calling this "a handsome provision" has a dry, ironic edge. It sounds generous, but it quietly admits that sight is now controlled and has a price.
The second stanza turns darker. "To see is to kill" suggests that simply watching, or intruding with our eyes, can do harm, perhaps to the wild things we disturb. Then night arrives "to help the fox," as though darkness takes the animal's side and hides it from human eyes. The speaker seems wary of the human gaze and sympathetic to the creature. The mood is hushed, cool, and a little defiant, with a sense that some places are better left unseen.