The Fitbit is a wearable fitness tracker that monitors activity levels, sleep patterns, and more. In the podcast, it's mentioned in a sarcastic context, suggesting that people can negate the negative health effects of unhealthy drinks like Coke by taking 10,000 steps while wearing a Fitbit.
"The podcast guest jokingly recommends wearing a Fitbit and taking 10,000 steps to offset the negative health effects of drinking Coke."