A blackhole is a huge region of …. well … blackness that has a huge amount of mass and sucks in anything within it’s orbit. Kind of like a whirlpool, but in outer space. You see, blackholes have a mass that is greater than their size so the gravitational pull is quite extraordinary causing anything that comes near to get sucked in with no hope of escape.
Black holes are born when stars die and can also be caused by other huge objects in space. Stars might live for thousands of years, but eventually their source of power gets used up and the star collapses. If the star is big enough, it will turn into a black hole. If it does not have enough mass, it simply becomes a dwarf star or neutron.
So, one might wonder, what happens if you get sucked into a black hole? At first you enter a state of weightlessness, you are light like a feather - sounds pleasant doesn’t it? But wait. As you get deeper into the black hole, your body gets stretched - longer and longer and longer until finally you are stretched into several pieces. Not so pleasant now, eh?
So definitely, blackholes are something to be avoided but an interesting part of astronomy nonetheless.