When Moses was told he was born a Jew and raised by Pharaoh's kingdom, Moses had to make a decision about his future.
Did he continue to watch the Jewish people as slaves under Pharaoh or did he help the Jewish people become free from slavery?
The answer came to Moses one day when he was herding the sheep. One sheep got away from the pack and Moses went after it.
While Moses was alone, he heard the voice of G-d as a bush was burning blue flames. It said to Moses he was chosen to free the Jews from slavery.
The burning bush is said to have been G-d speaking to Moses. Moses is considered a prophet since G-d chose to speak to him.