Imagine a scene in which a man is sitting on a park bench reading a book. A woman comes up and sits beside him. He looks up at her. She hands him a letter. "It's over," she says.
If you were to see this scene in a film, completely out of context, you might look for a variety of clues to figure out what's going on. Some are straightforward: How are the people behaving? What's her tone of voice? What do their faces look like? How close are they sitting? If you've spent some time thinking about filmmaking, you might consider other things: How are they framed? What's the angle of the shot?
