Hercules looks up at Mercury in this statue by Jules-Félix Coutan called Glory of Commerce. The third statue (Minerva) is not visibly in this picture.
According to The Secrets of Grand Central, Part 2 on the Untapped Cities website:
The statue “Transportation”, alternatively “The Glory of Commerce” adorns the front of Grand Central facing south. On the left sits Hercules, representing physical strength; on the right, Minerva, goddess of wisdom and protectress of cities; featured at the center is Mercury, god of travel and commerce. This sculptural grouping was considered the largest of its kind when it was built in 1914. Made of the same Bedford limestone façade as the Terminal, it is 48 feet high and weighs 1500 tons. Underneath Mercury is the world’s largest example of Tiffany glass, at 14 feet in diameter.
Though it was designed by the French sculptor Jules-Felix Coutan, then a professor at the École des Beaux-Arts in Paris, the artist himself never set foot in the United States. Asked if he would visit to oversee the construction of his piece he replied in the negative, explaining, ”I fear some of your [American] architecture would distress me.” The piece was instead constructed/assembled by William Bradley and Son of Long Island City, Queens. It took 7 years, whereas the building of Grand Central itself took 10.