Have you ever been in a place that was so quiet and so calm that it was disturbing to you? Colerdige, who was a good friend of Wordsworth lived for a while near him in the lake district of England. See link. It is a beautiful place, out in the countryside. In this part of the poem, Coleridge is sitting outside with his child cradled at his side by a fire. Everyone else in the family is asleep inside the cottage. He is meditating or thinking about life in general, but he finds the quiet disturbing, inhibiting his meditation of life. Life is going on in the sea, hills, and woods ---- insects, fish, birds, ----life in general, but it is going on so quietly as to be inaudible (unable to be heard). HIs fire has gotten to the point of a blue flame and is dying out and even the flame isn't moving. The only sound is the fluttering of a film on a grate nearby.
Although Wordsworth, Coleridge's good friend, loved the lake district, this was not a good time for Coleridge. He had been raised in the city, his marriage was failing, and he started taking opium. When he left the lake district, his life was in shambles and he never really recovered from it. See link.