Well, for starters, the colors (buff background and "Jersey Blue" details) represent the colors of the local troops during the Revolutionary War.
George Washington liked the colors so much that he adopted them as the official colors for all of his troops, even though most of them had to continue to wear their own clothing, due to lack of funding.
The two Goddesses represent the words that they stand above. The one on the left--"Liberty"--is holding a pole topped by a, "Liberty Cap", an icon of the Revolutionary era.
The one on the right--"Ceres"--represents the bounty of NJ's farms. The cornucopia that Ceres is holding symbolizes agricultural abundance.
There is much more to the symbolism depicted on the NJ flag, and if you go to
AboutNewJersey.com - New Jersey (NJ) State Symbols and Flag, you can read the details.