qu'est-ce que c'est que cette chose-là?

Easy to express concisely in English, but a much longer expression in French:

What's this thing?

Technically, he's really asking, "What's that thing?"  This is determined by the "là" at the end of the French version of the question.  Là comes from là-bas, which means "over there."  Change the -là to a -ci, however, and you're now asking about this thing.  Ci comes from ici, which means "here."