Not the type of namespace being referred to. In this case, it's referring to the requirement to refer to all types of a certain category with a keyword, as in `struct Foo`. In Rust, you can refer to a struct named Foo as just `Foo`.
I disagree. There may not be a keyword required to refer to `struct`s specifically, but the namespace that is searched when resolving a symbol is determined by the syntax used to refer to it. For example, in C++, you cannot determine whether `a` is a type or a value in the statement `a * b;` without knowing how it is declared, and C also has this ambiguity once `typedef`s are involved. In Rust, there are no such ambiguities (unless there's something I've missed).