Someone hears a wedding bell ringing in the distance, and the sound sets off a quiet reckoning. The speaker doesn't tell us who is getting married or who is listening, but the last line gives the feeling away: "twenty years of solitude." The bell is a signal of happiness and union, yet it reaches the speaker only faintly, as something that belongs to other people.
The repeated "far away, far away" works like an echo. It makes the sound fade, and it also suggests how remote the speaker feels from love and companionship. The verb "tolls" is interesting too, since we usually link it with funerals rather than weddings. That choice casts a shadow over the celebration, as if the bell marks something lost as much as something begun.
The mood is wistful and hushed, with a hint of resignation. The poem is only three lines long, and its brevity mirrors the emptiness it describes: there is very little to say, and a great deal of time behind it.