The features are what makes the app special. They are usually unique, in that no other app does it, or does it in the same way yours does!
The features are what will initially catch someone’s attention and make them want to find out more.
If your app’s features are not leaping out at you after you write them down, it may be time to re-think!
Write a list of all of your app's features and what they do. An example feature may be "A password keychain that lets you store passwords in a safe way".