Repetition of decorative elements and furnishings helps to establish a visual rhythm or feeling to the room. The design part comes in when you can experience how the room works.
Notice the lampshade, seating rattan stool and small table. They all allow air and light streaming from the windows to flow through them. In a living room, the sense of interconnectedness and lack of obstacles is important for conversation and connection to flow, too. (Check out the TV in the corner, not front and center as the focus of the room.)
The natural materials also create a symbolic link between the interior of the home and the beach outside.
When designing a room, consider what it is used for, and how that can be reflected in your decorations, furnishings, and space planning.