Lock any app using Secure folder.

[Surya230]

Follow these steps :-
1. Open Secure folder.
2. Add apps in Secure folder which you want to lock.
3. Long press those apps and click "Add to home." 

[arusha1234]

The purpose of secure folder is to create separate copies of apps and keep it in a locked folder. But an app lock locks a specific app and doesn't make copy