It's an idiomatic thing. You're never going to have 1-to-1 word for word translations between any languages. sein != zijn != to be != ser != essere. They have a lot of overlap because humans tend to talk about the same sorts of things in the same sorts of contexts, and all of these languages are fairly closely related but geographical separation means that they are not the same language. Dutch uses a bunch of different words to indicate "to be" in the sense of geographical placement, in much the same way that Spanish uses two words to differentiate between "to be" in a temporary/spatial sense and in a fundamental characteristic sense.