Anglicization is when we change things to make them more like what we're used to in England. So let's say you have a name that's really hard for English people to say - like Jóhannes in Iceland. If you move to England, people might change your name so it's easier to say - like John.
We anglicize lots of stuff, not just names. We might change foods or clothes to make them more like what we're used to. For example, if we see a type of clothing from another country, we might change it a bit to make it more like what we wear in England.
Sometimes, we might not even realize we're doing it. That's because we're so used to doing things a certain way that it just seems normal to us. But it's important to remember that not everyone is like us, and that's okay!