Kissing someone's hand as a form of greeting is a traditional expression of esteem and friendliness, especially towards elder women.
Hand-kissing is becoming rare, but it has not totally disappeared from the streets of Poland and Romania, although you might not meet a single hand-kisser for several weeks in either country.
The hand-kissing custom seems to come from the Middle Ages. When a vassal re-established his contract with his suzerain, he gave him a present, bowed and kissed his hand. In those days, gentlemen considered themselves as their wives' vassals too and it was thus right for them to kiss their wife’s hand like their suzerain's.
A man was required to remove his glove when kissing a hand. Removing one’s glove was a sign of respect: a small dagger could easily be hidden in a glove, so a naked hand was less threatening. Women, on the other hand, were not expected to disrobe their hands.