give someone a hand, Tohelpsomeonewithataskoractivity.
hand in hand, Together,incloseassociationorcooperation.
on the other hand, Usedtointroduceacontrastingpointofvieworsituation.
Word Origin
Language
Old English
Original word
hand
Originally meant
the end part of the arm
Background
The word 'hand' has been used in English since Old English times, with similar forms in other Germanic languages, such as Old High German 'hand' and Old Norse 'hǫnd'.