It can prevent data races in memory shared between processes in the same way it can prevent them in memory shared between threads. Data race prevention isn't built into the Rust language, it is constructed using a combination of the borrow checker and the type system.
As I understand the borrow checker, it wouldn't detect races that result from the interaction of separate processes, since that would be out of the bounds of the compilation unit. But my knowledge is limited in this, so I maybe wrong.
Rust has no concept of a process, same as it has no concept of a thread. So you'd build a safe abstraction for sharing memory across processes the same way you do today with threads.
