Translation:What is the square root of nine?
I think it's like "square" or "squared". The table may be square, but the root (3) is squared (i.e. multiplied by itself). Visualize a 3x3 box, with an area of 9. If the question is what is the square root, you're really asking what do you get when you take a square with an AREA of 9 (9 "squared") and look for the length of one side. That's the square root because if three is squared (multiplied by itself), it's an area of 9.
Oops, I reported an error with the audio that probably isn't really an error. I know that this is incorrect grammar, but I really hear "ποια ειναι τα τραγωνικη ριζα του εννεα" (note "τα" instead of "η") when played at normal speed. When I played it slowly, I now hear that "η" is pronounced "eta", which gives the "τα" when said quickly after "ειναι". First time that this "feature" of the speech synthesizer has lead me astray!