Hemingway's style has always been known as very terse. He is not one to waste words by any means. In general, you can see this in the fact that The Old Man and the Sea is less than one hundred pages long. While it's very short, you get to know the characters and their relationships. You can envision Santiago and the boy and what their lives have been like together.
Here's an example from the book. As you read it, think about what you KNOW from this short paragraph.
"They walked up the road together to the old man’s shack and went in through its open door. The old man leaned the mast with its wrapped sail against the wall and the boy put the box and the other gear beside it. The mast was nearly as long as the one room of the shack. The shack was made of the tough budshields of the royal palm which are called guano and in it there was a bed, a table, one chair, and a place on the dirt floor to cook with charcoal. On the brown walls of the flattened, overlapping leaves of the sturdy fibered guano there was a picture in color of the Sacred Heart of Jesus and another of the Virgin of Cobre. These were relics of his wife. Once there had been a tinted photograph of his wife on the wall but he had taken it down because it made him too lonely to see it and it was on the shelf in the corner under his clean shirt."
In reading this, you can see the entire shack, inside and out, even though he only uses a few words to do it. You also find out about his wife and his religion.
Enclosed is a style description from another of Hemingway's famous works, For Whom the Bell Tolls.