The form of expression is whatever helps to make the script uniquely yours. In one sentence he has helped to define a whole personality. Finding the style and expression that suits you best as a writer evolves over time. It has to do with personal taste and with established writing ability. Both those qualities are achieved only through writing and rewriting, discerning what best expresses what you see and finding the best words for it.
Some people come to that easily.
For others, it is work. But in the end, the style and expression of a script will help to lift it off the page and make it a movie.