It's more precise to think of unit as an empty tuple. A tuple is like an ad-hoc struct without names for the fields, so `(int, string)` is like `struct MyTuple { int a; string b; }`. An empty tuple would be `()` (which is the syntax for unit in many languages), meaning `struct MyTuple {}`. If you think about it, that's about the closest you can get to "nothing" without invoking type system handwavium (like void, which is basically "unit without the good parts but that can also mean anything").

You can do clever stuff with it, for example `HashMap<string, ()>` is practically identical to `HashSet<string>` (depending on how clever the compiler is, possibly actually identical).