Welcome to Android Central! Sorry, but are you seeing an option for "Phonetic Dictionary" and wondering what it's for? Or are you asking for a phonetic dictionary function?
If you use Chrome and start typing the word in the URL bar, it should start giving suggestions or guesses of what you're trying to type, so that's one way of figuring out the correct spelling. You could also try dictating the word (using speech to text) and seeing what Google comes up with.