Ništa means nothing.
You spend a long time looking for a present for your wife and finally find a cup in a niche in one shop – but it is too small, so in the end you buy nothing at all. Niche and cup (Tasse in German) give you ništa.
You know the word from chapter 2, from the sentence nemam ništa za prijaviti – here it stands on its own for the first time.