The mood of the poem is quiet and contemplative. The narrator has stopping in the dark evening to admire the snowy woods, and he is far from the village where the owner lives. The village would have lights, horses and pedestrians, movement and sound and life. The woods, by contrast, are dark and quiet, with no sound but that from the narrator's horse:
He gives his harness bells a shake
To ask if there is some mistake.
The only other sound's the sweep
Of easy wind and downy flake.
(Frost, "Stopping by Woods on a Snowy Evening," eNotes eText)
Without these distractions, the narrator can focus on the beauty of the woods and the meaning of his own life, spent bustling around "keeping promises" and "traveling miles." He would rather go into the woods and exist in the quiet and dark, but he knows that soon he must return to his busy life. This moment of contemplation is a small joy among the daily grind of work, personal interaction, and obligation.