I was wondering if for example you rub a balloon on a wool surface and create a negative charge by getting some electrons from it and put the balloon near your arm for example, is it possible for the electrons on the balloon to go through the human body?
It depends of the energy of the electrons, of course, but generally if it's passing through air it can also pass through human skin and tissue to some extent.
See beta radiation which is effectively electrons.
Can penetrate human skin to the stratum basel layer of the epidermis. This is where new skin cells are produced.
To put this in perspective, the epidermis, the outer layer of skin, is between .05 mm (on the eyelids) to 1.5 mm on the palms of the hands and soles of the feet. On average, it is less than 1/16th of an inch. The epidermis is made up of five layers.
Low energy electrons- like those transferred by rubbing that balloon on your arm- will not pass through your skin. High energy electrons that are produced in some types of atomic decay processes can go through your skin and penetrate into tissue, and as such are sometimes used in radiotherapy to kill tumors.