The No vote means that Greece will not submit to further austerity demands by the European Union and therefore will not get bailed out by them. That most likely means that Greece will give up the Euro currency and return to its own. And it may even pullout of the European Union altogether.
What we need to watch is Italy and Spain who are also in trouble. If these two nations follow suit with Greece and withdraw from the European Union then the EU will come crashing down. This could precipitate a world-wide depression. This is not a foregone conclusion so we will wait with baited breath to see what happens.