The Jordanian flag symbolises the Kingdom's roots in the Great Arab revolt of 1916 - its adapted from the banner of the revolt!!
The black, white and green bands represent the Arab Abbasis, Umyyad and Fatimid dynasties respectively, while the red triangle represents the Hashemite dynasty.
The 7 point Islamic star represents the 7 verses of Surat Al-Fatiha, the firts sura in the Holy Qura'n, and, also stands for the unity of the Arab people. Some believe it also refers to the seven hills on which Amman, the capital, was built.