Different depictions of the S-Shield on action figures and statues. Some worn by Superman, some by others.
The S-Shield is a symbol worn by Superman, Supergirl, and other Kryptonians who are members of the House of El, as well as by other superbeings who have joined Superman's battle for truth, justice, and the american way.
The symbol is the Kryptonian symbol for hope; it is also the family insignia for the house of El. In some versions, it was designed by Martha Kent as a symbol for her son Clark Kent to wear.
See also
Gallery
The S-Shield as seen in promotional material for Man of Steel.