The letters on the Ferrari logo, which look like "SJ" are actually "SF," and they stand for "Scuderia Ferrari." It is the racing team division of Ferrari that typically competes in Formula One races. "Scuderia" is an Italian word meaning "a stable for racing horses."
The word "scuderia" is commonly applied to automobile racing teams as well. The team is also named after its founder, Enzo Ferrari. The logo includes a prancing horse because it was the symbol on the Italian World War I ace Francesco Baracca's fighter plane. Baracca's parents were good friends with Enzo Ferarri and asked the entrepreneur to use the logo after the flying ace died.