This photo does a few things that I like.

The bird stands out from the background. This is helped by the background being mostly light monochrome colors and not a very busy background.

The Barn Swallow has deep colors that sets it apart form the rest of the scene.

Light is glinting off the Barn Swallows feathers.

Posture makes a difference. And the Barn Swallow with its wings back and tail to the side with tail feathers fanned out makes it interesting.

And the beep blue and orange colors are an interesting color combination on the bird.

Photo details: Nikon D300S. Nikon 300mm f/4. Focal Length 420mm. ISO 400. 1/1250 sec. f/5.6.