What does it mean to get an electric shock from touching someone, according to science?

Not completely, but there are ways to limit them:

• Wear clothing made from natural fibers (cotton, linen).
• Drink enough water and moisturize your skin regularly.
• Use a humidifier in winter.
• Touch a metal surface (like a doorknob) with a metal object before shaking someone’s hand: the charge will dissipate painlessly.
• Opt for shoes with conductive soles if you are particularly sensitive.

Bottom line:  No one is « electrocuting » you out of mystery or with a hidden agenda. It’s nothing more than a little play of electrons… made perceptible by a static discharge.