The code example is a good example of information hiding.

Because the language strings are hidden inside a function, you add code that looks at a locale setting to switch language without the caller needing to know.

And you can make use of this function from many places, while always knowing that there is a range check performed. Directly accessing the array means you are distributing the responsibility for such things into an unknown number of places.

Encapsulation really is one of the cornerstones when discussing software design. This is similar to C++ objects with "get" methods to retrieve actual attribute values, to be able to change the real implementation without the users needing to know and adapt.