There is a new scam where hackers send you a text that asks you about a password reset on your gmail account, and if you did not, text STOP. This is a scam. The bad guys asked for that password reset and now want you to send them the authorization code! Don't fall for it.
Remember that Gmail or any other web email service will never ask if you *don't* want to do something with your account. You didn't ask for a password reset, so you shouldn't be asked about one.
Do not reply to the text (doing so will tell the scammers that they have reached a valid number). And to prevent losing your account to bad guys, it's a very good idea to have 2-step verification set up on your Google account.