Question

why does a charged body loose its charge if touch it with our hand?

Answer 1

because when we touch a charged body it connects with the earth through our body
and can gain electrons from earth if it is a positively charged and lose electrons if it is negatively charged. This process of transferring of electrons from a charged to the earth is called earthing

Answer 2

As we know our body is a good conductor of electricity. A charged body loses it's charge when we touch it because the charge is transferred to the earth and our body works as a conductor between them. Thus the charged body loses it's charge and become neutral.

Hope it's right :)