I am going to assume that this question is referring to the Robert Frost poem "Mending Wall."
The narrator of the poem is the person that initiates the mending of the wall. When the poem begins, the narrator is contemplating the fact that something exists that simply doesn't want walls to exist.
Something there is that doesn't love a wall,
The speaker then goes on to give two examples of "something" that repeatedly destroys his wall. The first thing is the weather. Alternating freezes and thaws eventually put large gaps in the wall. The second thing is hunters that tear apart the wall, so their dogs can hunt the rabbits.
Where they have left not one stone on a stone,
But they would have the rabbit out of hiding,
To please the yelping dogs.
The narrator then brings his reader back to the task at hand. He is mending the wall; however, the poem says "we." This lets readers know that the poem's speaker is not the only person present at the wall.
The gaps I mean,
No one has seen them made or heard them made,
But at spring mending-time we find them there.
The other person is the narrator's neighbor, and the narrator states that he let his neighbor know about the wall needing to be repaired. The two men meet on a predetermined date and each work on their own side of the wall to mend its broken sections.
I let my neighbour know beyond the hill;
And on a day we meet to walk the line
And set the wall between us once again.