If you see Profile locked on someone's profile, that person has chosen to lock their profile and show a limited view of their profile content to people they are not friends with on Facebook.
Locked profiles are only available in some countries, so you might not be able to lock your profile. But don't worry—adjusting Facebook's privacy settings to get the same effect as a profile lock is easy.
How to Lock Your Facebook Profile in 3 Easy Steps - wikiHow
One way to limit people's access to your Facebook profile is to lock your profile. Doing so severely limits what's visible to the public on your profile. We'll show you how to do that on Facebook on desktop and mobile. What Happens When You Lock Your Facebook Profile?
Learn how to lock your Facebook profile on Android, iPhone, and desktop to protect your privacy from strangers.
Want to protect your Facebook profile from stalkers? Find out what is a profile lock on Facebook and how to lock your Facebook profile.
Learn how to lock your Facebook profile with our simple guide. Get clear, step-by-step instructions for iPhone, Android, and desktop to control who sees your information.
Learn how to lock your Facebook profile for maximum privacy. Follow simple steps to make your account secure on mobile or desktop.
To enable the feature, tap on Profile icon > Facebook name > 3-dots icon > Lock Profile. However, users can still search for you on the platform and send you friend requests and messages.