Areaction produces 0.883 moles of h₂o. how many molecules are produced?

The answer is 5.32 × 10²³ molecules

Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance:
6.023 × 10²³ units per 1 mole

We have 0.883 moles.
If 1 mole has 6.023 × 10²³ molecules, 0.883 moles will have x molecules:
1 mole : 6.023 × 10²³ molecules = 0.883 moles : x

x = 6.023 × 10²³ molecules * 0.883 moles : 1 mole = 5.32 × 10²³ molecules