The speaker describes sitting with a fixed expression, one that has spread past their face and into their emotions too. It's a mask that has stopped being a mask and become the real thing. Then comes the word "BANK," broken into single letters stacked down the page. The poem doesn't explain it, so it's open to interpretation. It might suggest a blank, a wall, or something closed off and empty, like a vault. The vertical letters also slow the reading down and make the gap feel physical. The title, "Lacuna," means a missing piece or a gap, which fits that sense of absence.
The ending is the most revealing part. "All I feel is nothing" is flat and blunt, yet the speaker still says they thought they were getting better. They quickly correct themselves: "Well actually I guess in a way I am..." The trailing dots leave it unresolved. The mood is numb and uncertain, with a hint that feeling nothing might be better than feeling pain, though the speaker doesn't sound convinced.