Kyle is interested in Google Fi and wants to know how they calculate the data charges. Leo says that Fi is a better deal than T-Mobile if he uses less than 5GB of data a month since they charge $10 per GB. If he uses more than that, then T-Mobile is a better deal. Google Fi would give him T-Mobile, US Cellular, and Sprint service all merged together.
The other thing to consider is that Google Fi only works with Google phones like the Pixel or last year's Nexus. He could put a Fi card into another Android phone, and it will work, but he won't get the benefits of it hopping across different networks.