I don't think if it's available at the game option. You can try looking there and of course it would be hard to understand cause it's not in English. Anyways, perhaps you can reinstall it again and choose english during installation.
The langauge of the Sims (both Sims 1, 2 and 3) has always been simlish.
It's part of what makes the game so cute
Just listen to the tone of what's said. Then you'll understand it easily