The Orion constellation is a very dynamic section of sky, home to a host of interesting objects. This particular image is a deep exposure of the region of sky around Orion’s Belt.
First, the three bright stars you see are the three stars of Orion’s Belt. In this image, the lowest of the stars is Alnitak. Below Alnitak, you can see the Flame Nebula and just to its right you can see the famous Horsehead Nebula. Near the upper right you can see the M42, also known as the Orion Nebula. Immediately to the left of M42, you can see an open cluster of stars sometimes referred to as the Running Man.
Most of the objects pictured here are about 1,500 light-years from Earth and the image itself spans a distance of 75 light-years.