In this poem, the speaker compares the "measured" and slow beat of the village blacksmith's hammer as he pounds the metal in his smithy to a "sexton ringing the village bell." He uses a simile to compare these two unalike things—the pounding of a hammer and the chiming of a bell—pointing out the way in which each can be said to ring. Not only do these objects sound alike, but they both also seem to possess the same careful and slow pace.
A sexton is a person who is associated with a church, someone who might care for or maintain the property, ring the bell for services, and so forth. In comparing the blacksmith to the sexton, the narrator seems to elevate the smith, connecting him to the divine in ways that the average person might not typically think of.
The narrator goes on to describe how faithful the smith is, how loving he is to his family, and how he misses his dead mother and has to wipe a tear from his eye when he thinks of her. He is such an important, and perhaps oft-overlooked, person, who toils and works so hard all his days. He is not any different from one who serves God in what seems like a more direct way. The reference to the sexton compels us to consider how important and godly a role is played by the blacksmith.