The goal of the zig language is to allow people to write optimal software in a simple and explicit language.
It’s advantage over c is that they improved some features to make things easier to read and write. For example, arrays have a length and don’t decay to pointers, defer, no preprocessor macros, no makefile, first class testing support, first class error handling, type inference, large standard library. I have found zig far easier to learn than c, (dispite the fact that zig is still evolving and there are less learning resources than c)
It’s advantage over rust is that it’s simpler. Ive never played around with rust, but people have said that the language is more complex than zig. Here’s an article the zig people wrote about this: ziglang.org/learn/why_zig_rust_d_cpp/