Cinema is always considered to be a great way to understand a time period or a society. A well made film can provide a glimpse into society, albeit through the eyes of the film maker; and cinema has often been used as a powerful tool for political or social commentary.
Cinema, by its very nature, has the potential to be a multilayered form of communication. Films could have several themes running through it such as power, relationships, violence, crime, love, food, architecture or anything else that might take the film maker's fancy; and these themes could run in the background of the story, taking the story forward.
Films are regularly used teaching aids in a variety of subjects, including sociology, politics, anthropology and language. English films could well be used as an aid in English language courses as they would give an idea of colloquial language and society. So if you're taking an English language course in Wales, or in fact anywhere in the world, do not be surprised if some films are part of your syllabus.
Cinema is a great way to understand a particular culture or community. Cinema from different parts of the world is bound to have different recurring themes, different cinematographic style and a different way of storytelling depending on the culture, customs and reality of that place.
Obviously, the film maker affects the film. So the background and influences of the film maker is key to how the story holds together and how it is told to the viewer.