Let’s say you want to call a variable module. Er, that’s sort of tough, because, when you write module in the source code, it thinks it’s a ModuleExpr or something and there are errors when trying to compile.
To fix this, you can write a backslash before the token you would like to treat as an identifier. So, by writing \module in the source code, you could feasibly call a variable module.
You could also use this to call a variable any other keyword in the language, like \if for if, or \return for return. This means that, ideally, the language itself should never get in the way of the programmer.