Theme 21-2 is the second level of the second episode of the world, Bad Piggies in the game, Angry Birds.
Shoot the Boomerang Bird to activate the TNT. Then, shoot the Yellow Bird at the balloons holding up the 2 wood squares. Shoot the next Yellow Bird at the nearest wood house holding 2 helmet pigs and one helmet pig. That should leave you with 1 Boomerang Bird left, giving you 10000 points. You should get 3 stars for defeating the level.