「日本語を話さない、フロスティ。」 "Nihongo wo hanasanai, Frosty." is an actually correct way of saying: "I don't speak Japanese, Frosty.", which I'm pretty sure that's what he meant in the first place.
Moral of the story: Don't trust online translators, especially when inputting a grammatically wrong sentence in the first place.
By the way, the subject on the Japanese phrase I wrote above is omitted, but it could be any of those:
私 watashi
僕 boku
俺 ore
あたし atashi
All four above can mean the same as the "I" pronoun, but carry different connotations (unisex formal but sometimes feminine, male and may be childish or naive, male and arrogant, strong and/or manly; and female, respectively). Plus, there are more words that mean "I" besides the four above, but those are the most common.
And that's it for the small Japanese lesson you may or may not find interesting.