I've encountered 'dłoń' only in poetry
Here is your answer, POLONIUS3, it's a lyrical song, it's like he was singing about kissing this lady's eye, feet or any other body parts, but in normal speech we use "całować kogoś w rękę" (to kiss somebody's hand, a traditional greeting, still present among older generations, normally only women are kissed by men, except for religious figures like the Pope - but it's a different kiss, not a greeting, but gratitude), not "całować czyjąś rękę".
There's also a figurative expression "całować kogoś po rękach" = to be very grateful/thankful to someone.
Generally in Polish 'ręka' is often used where in English you'd say 'hand' or 'arm'.
Here's the medical (anatomical) description
(hand) is divided in:
(wrist) - which is often considered a separate body part, between the forearm and the hand,
(palm), inner part of the hand (I'm not sure how the outer part of the hand is called in Polish, because it's not used too often),
(fingers, including the thumb)
In colloquial language, however, the word forearm is almost not used (we say 'ręka' for it), and the word 'ramię' [plural: ramiona] is quite often used not for the 'arm', but for the 'shoulder', unless you need to be specific for the medical reasons.EDIT: While I was editing my post z_darius wrote something similar in a shorter way :)