Bowdlerisation is a big word that means changing something in a book or story to make it more "appropriate" for some people to read. It is named after a man called Thomas Bowdler who did this a lot in the past.
For example, imagine you are reading a story about a very bad person who does mean things to other characters. But some people might think that the story is too scary, or the bad person is too mean, or there are words or scenes that are not good for children to read.
So, bowdlerisation is like taking some of the scariness or meanness out of the story. It might mean changing some of the words or sentences or even completely removing parts of the story.
But sometimes this can also change the original meaning of the story and make it less interesting or important. It's like watching a movie that was edited for TV - it might not be as good as the original.
So, some people like bowdlerisation because it can make some stories more comfortable to read, but others don't like it because it can change the original story too much.