"How many words are there?"
Translation:כמה מילים יש?
It's fine if you want to ask "How many words are [there] there" -- i.e. how many words are there in that place. The English "there" can be positional or existential, but I guess the intention here was either (1) to ask how many words exist at all -- an absurd question, but not beyond Duolingo levels of absurdity -- or (2) somebody asking about the number of words in a particular piece of writing, maybe a dissertation or an article that someone has submitted for publication, something like that.
It's the refrain to a song, אליעזר בן יהודה, about the developer of the Modern Hebrew language. You can hear it at https://www.youtube.com/watch?v=Jt2gLGvLKW0&feature=player_embedded, with Moti Caspi singing.