By default, your friends list on Facebook is “Public.” It means that anyone can see it.
If you don’t want others to see your Facebook friends list, then you can hide it. Here’s how you can do it on Facebook web version (PC) and app (Android):
In the “How people can find and contact you” section, you can see “Who can you see your friends list?.” Click on “Edit” link beside it.
Now, you can see a drop-down list. Open it, and then choose “Only me.”
That’s it. From now on, only you can see your Facebook friends list and others can’t.
Open the Facebook app.
Tap Hamburger icon (three vertical lines) > Settings & Privacy > Settings > Privacy Settings.
Now, tap “Who can see your friends list?” option which you can find it under “How People Find and Contact You” section.
Tap “Only me” option (if you didn’t see this option, tap “See More” and then you can see this option).
That’s all. From now on, only you can see your Facebook friends list and no one else can.