The chemical reaction you've written is not balanced. Here's the balanced chemical equation for the reaction between sodium (Na) and water (H2O) to produce sodium hydroxide (NaOH) and hydrogen gas (H2):
2Na + 2H2O -> 2NaOH + H2
This balanced equation shows that two moles of sodium react with two moles of water to produce two moles of sodium hydroxide and one mole of hydrogen gas.