This verse provides context for the summary in 1:1 and the detailed description in 1:3–2:3. God's words of creation bring order to the universe's chaos.
formless and void (Hebrew tohu and bohu): This phrase means something like "wild and waste." It strongly contrasts with the final ordered state of the heavens and earth (1:1).
surface of the deep (Hebrew pene tehom): Some scholars suggest this refers to the Mesopotamian goddess Tiamat (representing chaos). But Genesis sees tehom as empty chaos, not as a deity or goddess that God fought in a cosmic battle.
the Spirit of God: God directly guided and oversaw the process of creation.