The robot not only looks like a human but also is designed to work like one. With human-like hands and arms, R2 is able to use the same tools station crew members use.
For the mission in September, engineers plan to monitor him closely to see how he operates in weightlessness. Plans eventually call for R2 to perform tasks that would normally require astronauts to take spacewalks. The hope is that at some point in the future robots will be able to perform spacewalks and other tasks too difficult or dangerous for humans. For now, R2 is still a prototype and does not have adequate protection needed to exist outside the space station in the extreme temperatures of space.
For more, check out the page on Robonaut at http://robonaut.jsc.nasa.gov/