A black hole can be compared with a trash can. All mass in the neighborhood will end inside the hole. Not only the mass will end, but also time of that mass.
When you throw things into a trash can, eventually the can cannot hold anymore garbage, till you empty the can, but in a black hole, the mass of the garbage will stop in existence. One important fact is, that the information of the mass will be in a kind of memory. That differs from a trash can, because do you know what you have discarded a month ago? The black hole remembers it. Not only from the last month, but from everything that has been swallowed by the hole. Even the information that comes from other black holes, which are swallowed. Eventually all mass in Universe will end inside one black hole. I will write about that in my article about the beginning of life, which will tell us how Universe will get its existence and how it will end.
Everything in space that is not needed anymore, eventually will end in a black hole. It also ends galaxies that has no existence anymore.
Black holes will not end galaxies that are still in progress. Like our galaxy. We have one or more black holes, but they just clean up what is not used anymore.