A speaker sits on a train and notices the face of a stranger, caught in strong sunlight. Instead of looking away, as people usually do with strangers, they look closely at the freckles and spots and start reading the skin like a record. Every line seems to show something: laughter in some, frowning in others. The comparison to a used leather bag is a nice, unexpected touch. It suggests that wear isn't damage but proof of a life actually lived.
The speaker feels tender curiosity. Words like "human" and "vulnerable" show they are moved by how exposed this person is, even in an ordinary public place. The poem ends on two questions the speaker will probably never get answered, which gives it a quiet, wistful mood. It's gentle and observant, and it captures that brief feeling of realizing that everyone you pass has a whole hidden story behind their face.