There is no cheat code to make Sims speak English in any of the "Sims" games or expansion packs. In all iterations of "The Sims," the Sims characters only speak Simlish, which is not intelligible as any language in particular.
The creators of "The Sims" developed Simlish as a language that is more or less gibberish, allowing players to imagine what their Sims are actually saying. However, there are several English interjections that appear to be part of the Simlish vocabulary, including "yuck" and "ouch." Even though there is no code as of 2014 that enables Sims to speak English, there are numerous other "The Sims" games cheat codes with varying effects.