You've posted this question in the wrong group, but I'll give you an answer.
"Go Down, Moses" is about the exodus from Egypt of the Hebrew slaves, led by Moses. This song is important in the African American tradition because the plight of the Hebrews mirrors their own struggle for freedom.
As for Israel, the Hebrew people were not called Israelites until after the exodus.
Most scholars believe that the pharoah at the time of the exodus was Ramses II because the book of Exodus in the Old Testament says that the Hebrews were building the Egyptian store cities of Pithom and Raamses, which were built during Ramses' reign.
Moses was the leader of the Israelites. He had been adopted by Pharoah's sister, but chose to return to his own people and was called by God to lead them out of slavery.
The eNotes study guide draws parallels between the Hebrews and the African American slaves:
Both were slaves forced to endure abominable treatment. Families were torn apart. Biblical Hebrews and Africans in America alike were beaten, exploited as labor, killed at the whim of an overseer. Although the song does not specifically mention any of these facts, it effectively sums up all the hardship in the simple phrase, “Oppressed so hard they could not stand.”
By using the form of song, the African Americans could take the place of Moses in saying, "Let my people go."
Actually, the poem is about slavery.
Pharoah: slave owner
Moses: underground railroad cunductor
IDK what isreal is though...
but yeah, we are learning about this poem and its in the same group with all the other slave poems.