How to explain a progam

How can I explain a program?

I don't know if you have seen the movie 'her' but that is Joaquin Phoenix's job in the movie.

There is this computer program that allows you to write what you say. You say what you want the program to write and it writes it in a word document. It doesn't write it in print but in manuscript as if you had hand written the letter.

Is this sentence question correct?
How can I explain a program?
Would you phrase it differently?

Thanks