In just three short lines, Dave Bonta sketches a small, ordinary moment: someone at the office, caught up in work, eating a chicken wing. There's no big event and no stated emotion, which is part of what makes it interesting.
The title, "On the fly," does a lot of the work. It suggests eating in a hurry, squeezed in between other things. But a wing is also something that flies, so the phrase carries a small, dry joke. The speaker is grabbing food on the fly while eating a part of a creature that once could fly.
The phrase "busy about business" sounds a bit stiff and repetitive, as if the speaker is mocking office life's empty busyness. The mood is wry and quietly detached. The speaker seems neither angry nor unhappy, just amused, noticing how mechanical and slightly absurd it is to be fed and occupied at the same time. The poem judging by its tone, hints at a gap between the natural world and the workplace, without ever spelling it out.