Chris has a friend who is using the beta version of iOS 10. How can he get it? Leo says that iOS 10 is a public beta and he can sign up and download it from Apple at beta.apple.com. Chris should understand that this is pre-release software and it could cause some of his software and apps to stop working. It may also make his iPhone unreliable.
This is a controversial update, and it won't really be all that useful now because many of the functions will only work with other iOS 10 Beta users. Chris can help provide feedback during the development until it's release, though. Leo has it on his iPhone and he likes it, but his main phone is an Android phone, so he doesn't have to rely on it day to day. That's why Leo says that if it's his main phone, he'd advise against upgrading until the final release this fall.