why should you not touch electrical appliances with wet hands
Water can conduct electricity ( if it is an electrolyte, as most tap water is) so you shouldn't touch electrical appliances with wet hands, or put them near water in case the water completes a circuit from the appliance, resulting in a live circuit.if you touch a live circuit that could result in electrocution.
Because water which contain ions can conduct electricity. Example- if you take tap water and pass electricity then tap water will conduct electricity because you know tap water contain ions. Not only tap water, every electrolyte(substance that contain ions) can conduct electricity like salt water,HCL,e.t.c. But if you take insulators or non-electrolytes(substance that doesn't contain ions) can't conduct electricity, e.g;distilled water,urea, e.t.c.