As the story of Moses continues we see that Moses had fled from Egypt because his life was threatened. Ex 2:15. He fled to the land of Midian for safety. There he meets Jethro who gave him work as a shepherd and also gives him one of his seven daughters, Zipporah as his wife.
In process of time God commissions Moses to return to Egypt and confront Pharaoh about letting the Israelites go free from their bondage as slaves.
Zipporah and the two sons accompany Moses at the start of the journey. Along the way something very strange happens and scholars are sill debating about it.