The title poses a question: is the speaker a tailor or a sailor? The poem suggests he can't be both, and the tension between the two lives is what drives it. In the first couplet, a man with pins in his mouth is the picture of a tailor, someone used to small, careful, indoor work. Putting him on a ship looks like a dangerous mistake, since one lurch of a wave and he could swallow the pins.
The second couplet turns personal. "My chest full of wind" could mean the speaker is full of longing or restlessness, a pull toward the open sea. Yet he "cannot fill" his belly, so the wind brings no nourishment. Judging by the imagery, he feels a gap between what he yearns for and what he can actually live on.
The mood is wry but uneasy. The poem is short and almost joking, yet it hints at someone stuck between a safe trade and a restless dream, with neither quite feeding him.