Annaliza is correct. The expression does mean stop harassing or bothering someone. But, the expression is figurative (paints a mental picture), not literal (exactly what the words say). To understand the figurative expression, imagine the literal expression "get off my back" which literally would mean that someone jumped on your back and created a heavy load (a great burden) for you to carry. So, if someone were harassing you or bothering/annoying/pestering you, that would be stressful for you, and you would want to tell that person to stop = get off my back.

whenever you feel someone is pressuring you to do something you can say it.... "get off my back......leave me alone...." " if you dont get off my back Im going to get really angry" "hes been on my back for the last 10 days...He wants his money, but I dont have it yet" It can also be used interchangeably with "hes on my case" which means the same thing

'Get off my back' idiom means stop harassing or bothering someone. Example You need to get off my back for breaking the pot because I apologized!