Lines in art indicate form as well as movement. It can also indicate value and a light source in drawing. This picture illustrates this because the lines go on and on.
Shape and form in the visual arts, shape is a flat, enclosed area of an artwork created through line, texture, color, or an area enclosed by other shapes. Form can refer to a three dimensional composition. This picture illustrates this because the ice looks 2 dimensional but is really a form because it's 3 dimensional.
Space deals with giving an illusion that something goes on for a distance. This picture shows space because the balls stretch from the front to the back of the picture
Balance is what creates a feeling of stability. The photo shows that because the photo is obviously balanced and centered by the person on the tight rope.
Unity shows that everything in the photo fits and goes together. For example this shows unity because everything is within the same colors and all the swans together.
Variety in art is when it's diverse and it isn't the same things in it over and over, and keeps the viewer interested. This picture shows variety with all of the different colors.