The speaker admits to feeling clumsy in two very different areas of life. At first it seems to be about physical work: building things with wood, hammering nails, tying knots. The speaker can picture the finished object perfectly, but the hands won't obey. Nails bend, knots slip, and even the body's nerves seem to "retract, distort," as if the gap between idea and action can't be closed.
Then the last two lines turn the poem toward speech. Making small talk is described in the same way as carpentry: something others do easily, but the speaker feels like a "novice" at it. That comparison suggests the poem is really about a wider sense of awkwardness, of not fitting in with ordinary skills. The mood is quiet, frustrated and a little self-deprecating. The speaker doesn't rage or complain, just states the facts plainly, repeating "I am unskilled" like a confession. There's also some sadness in a mind that sees clearly but can't make that clarity real.