It is worthwhile to note that the above is highly reductive. A “black hole” is the sort of “hole” in spacetime you’re thinking of. It is caused, however, by gravitational dilation of spacetime by an incredibly high energy density. If you stuff enough matter and energy into a tiny enough space, the gravitational force will be strong enough that no other force in the universe can keep it from getting closer, and closer. Even the forces which keep neutrons and protons from combining with each other will be surmounted, as the energy density increases asymptotically toward infinity. This tiny point of effectively infinite density is the black hole’s “singularity”. Surrounding this singularity is a region where anything (matter, light, space itself) that gets within that range cannot escape. This is because objects have escape velocities based on their masses. If you’re going fast enough, you’ll fly away from the earth never to return. If you’re not going that fast, eventually you’ll fall back down. The further you are from the earth, the easier it is to escape it. The “black” part of the black hole, called the “event horizon”, is the distance from the singularity at which the black hole’s escape velocity is equal to the speed of light, meaning that, closer than that, nothing can escape it. Hence why it’s “black”, because no light is escaping from it. Technically, a black hole is not perfectly black due to hawking radiation, and a black hole with a 0.5 meter schwarzchild radius would probably be small enough to visibly glow (just a bit). (probably not, see below)