When someone does something to help you,you should do something helpful in return,shouldn't you ?This is a phrase which has about the same meaning as " one hand washes the other ",don't you think so ? Anyone who has several hard tasks to do, feel really relieved and grateful if there is a "little help from their friends".
http://www.macmillandictionary.com/dictionary/british/relieved
By the way ,do you remember this famous song composed by the Beatles: With a little help from my friends ?Let's listen and sing along with them once again.Then you may listen to a conversation with the phrase; "One good turn deserves another"just clicking on the second link in this post,ok ? It is from The English We Speak program from BBClearning english.com.There is also the video to watch which contains this phrase as the moral of the fable.
Enjoy !
https://www.vagalume.com.br/the-beatles/with-a-little-help-from-my-friends.html
Resolva exercícios e atividades acadêmicas
http://www.bbc.co.uk/learningenglish/english/features/the-english-we-speak/ep-160517