Whenever you mix sodium hydroxide with an acid, you get the sodium salt of the acid and water. In the case of H2SO4, it is sodium sulfate.
2NaOH + H2SO4 --> Na2SO4 + 2H2O
For other acids:
NaOH + HCl --> NaCl + H2O
NaOH + CH3COOH --> CH3COONa + H2O
NaOH + HNO3 --> NaNO3 + H2O
etc....
This also usually works with other metal hydroxides.