Electrical current is created by the flow of electrical charges which often refers to flow of electrons through a wire or both electrons and ions.
Pure water, cannot allow for the flow of electrical current. However, impurities in water such as sodium ions allows for the electrical current to flow.
When someone touches a naked wire, or the water in which a live electrical wire is immersed, then their bodies, which is has many ions will have the electrical current to flow through. This might cause physical injuries typically referred to as shock.