What happens if you go near a black hole?

When you get near a black hole the exact effects depend on the size and mass of the black hole. A "stellar-mass" black hole - a black hole that's a few times the mass of the Sun - exerts a strong "tidal" pull on any object that approaches its event horizon. That is the same effect that creates the tides on Earth: the gravitational pull on the side of the object that is closest to the black hole is significantly stronger than the pull on the opposite side, so gravity stretches the object and pulls it apart.