He says, when the people ask what is the name of this God, what am I to say. Moses knew which God he was speaking with. Moses also knew that after 400 years many of the Hebrews worshiped the false gods of Egypt. He wanted some assurance. This is the first revelation of God's name.
Names are always important in Scripture.
We pronounce it Yahweh . He is not an abstract force. Because He is a person, we can have fellowship with Him. He has no beginning. All creation depends on God for continued existence.