If you see the lock symbol 
When someone locks their profile, only their friends will see the following:
- Photos and posts on their timeline.
- Their full size profile picture or cover photo.
- Their Stories.
- New posts and photos.
In addition:
- Any posts they’ve shared in the past to Public will change to Friends.
- Timeline review and tag review will be turned on.
- Only a portion of their About info will be visible to everyone on their profile.
Other ways to manage your privacy:
If locking your profile isn’t available to you, you can control your privacy in other ways through your privacy settings:
- Use Privacy Checkup.
- Choose who you share posts, photos and other information with.
- Edit basic info and choose who can see it.
- Change your story privacy settings.
- Turn on Timeline Review.
- Turn on tag review.
- Turn on Profile Picture Guard.
- Control Who Can Friend And Follow You.
- Control who can look you up using your email or mobile phone number.
Source: FB
