Characters with this skill can interpret the lines on a character's hand and make predictions about health, romance, destiny, and life expectancy.
They have acquired the skill of reading palms, possibly from travelling or circus people. Palmistry is a form of Divining mainly used for entertainment, enabling the character to earn a little money, much as would a street musician. Characters with this skill have a +10% modifier to Busk tests.
On a more practical note, characters can actually learn information about other characters. The gamesmaster decides what information the character discovers and they should present information in a fairly ambiguous manner, yielding useful information if the circumstances are right. Information could be about personality, intentions, or family detail.
See Divining for more detail on divinations possible with palmistry.