This image was taken by Gregory Harbaugh during the second spacewalk of the repair mission. The astronaut in the image is Joseph Tanner; you can see his mission checklist attached to his left arm as well as Gregory in the reflection of the visor. Just over Joseph’s left arm, you can see the aft section of the Discovery. A little further in the background you can see the Earth. Even further in the background, you see the Sun providing some intense and dramatic light.
In space, the Sun (and the ‘sky’ in general) looks very different because there isn’t an atmosphere to scatter its light. Because of this, the sun is very bright and the surrounding sky is very dark.