If you see the word "Live" on a contact's name in Find My Friends, this means that they are currently sharing their location. You can see their current location on a map, and their movement will be tracked over time. This feature is only available when both of you are using iPhones running iOS 15.
Previously, the app only showed an approximate location as of the last time their phone checked in with Apple's servers—a period that could be anywhere from minutes to hours. The "Live" option eliminates this problem and makes the app a powerful tool for keeping tabs on connected friends and family, whether you're worried that they are stuck in traffic or late for an impromptu meeting in unfamiliar territory.
If a friend's location is no longer appearing on Find My Friends, there may be an issue with their cellular or Wi-Fi connection. The other possibility is that they have disabled location services on their iPhone. You can check this by opening their Settings app and ensuring that Location Services is toggled on. If this is the case, try restarting their iPhone and re-enabling the service.
If you'd rather not wait around for a friend to re-enable their location, there are many tools on the market that will allow you to fake your own location. However, be careful—these tools can expose your private information to hackers. A better solution is to use a jailbreak-free tool such as iMyFone AnyTo.