From the Central Park website:
"Sculptor: Stanislaw Kazimierz Ostrowski
(1879-1947)
Date: 1939
Placed in Park: 1945
Donor: Gift of the King Jagiello
Monument Committee
Material: Bronze
The sculpture was chosen for the 1939 World's Fair in New York. Later that year, the Nazis invaded Poland, preventing the sculpture's return to its homeland. In 1945, it was placed in Central Park by the Polish government as a symbol of the proud and courageous Polish people. It portrays King Jagiello, the Grand Duke of Lithuania, who united Lithuania and Poland and became king after marrying the Queen of Poland in 1386. The monument depicts the moment at the Battle of Grunewald of 1410 when the King crossed over his head the two swords handed to him by his adversaries, the Teutonic Knights of the Cross.
Under the watchful eyes of King Jagiello, the blue stone circle at the east end of Turtle Pond is the site of weekend international folk dance gatherings."
More info about King Jagiello at Wiki: http://en.wikipedia.org/wiki/Jogaila