The poem is a tiny snapshot of a meeting, and it turns on a contrast. On one side is the dull machinery of the occasion: "paper proceedings," the agendas, minutes and documents that fill a room like this. On the other is a single human sound, "his full laugh," which rises over all of it.
The speaker doesn't tell us who "he" is or what set him laughing, and that gap is part of the charm. What we get is the speaker's attention. Out of everything happening in the room, the laugh is what they notice and hold onto. The word "full" suggests it is open and unguarded, not a polite chuckle. Judging by the way the poem is built, the speaker feels warmth and perhaps relief, as if the laugh briefly reminds everyone that real people are sitting behind the paper.
The mood is light, quietly affectionate and a little amused. Even the short lines feel like a small breath of air in a stuffy room.