2NaOH + H2SO4 → Na2SO4 + 2H2O
Recall that, in general, acids are H+ (a hydrogen or hydronium ion) and a negative ion combination, and bases are a positive ion and OH- (hydroxide ion) combination. And the general reaction between acids and bases yields a salt and water. It could be written like this:
acid+ + base- → salt + water
This is the Arrhenius definition of an acid-base reaction, and it is a Nobel Prize winner (1903) which has needed little modification to carry it into the modern chemistry laboratory. A link is provided to the Wikipedia post on this particular definition, and it's short and easy to read. Why not surf on over and check it out? It's a key element in unlocking the big, big world of chemistry (much of which, sadly, remains hidden from a large portion of the population - who benefit directly from it every single day of their lives). Oh, and wouldn't a link be nice? Hey, this is WikiAnswers. We got yer back. The link is provided. And we promise not to Rickroll you.