Password my applications

Unless the developer of an app provides a locking

feature, you cannot password-protect individual apps.

You can protect all your apps as a group by using a

screen passcode on your iPhone.

iPhones are single-user devices and not meant to be

shared. if you give someone physical access to your

iPhone, they can see/use anything on the iPhone.

Assuming your iPhone supports Touch ID, this

link will give you a start on setting it up:

Use Touch ID on iPhone and iPad - Apple Support