Then God said, “Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.”Genesis 1:6
God (‘ĕlōhîm) divided the “waters from the waters” with a firmament.
“Firmament” is translated from the Hebrew word rāqîaʿ, and can mean extended (solid) surface, or expanse.
This word is also found in Psalm 150:1.
“Praise the LORD!
Praise God in His sanctuary;
Praise Him in His mighty firmament (rāqîaʿ)!”
“Divide” is translated from the Hebrew word bāḏal, and can mean separate, divide, and difference, among a few other things.