A native mobile app is a smartphone application that is coded in a specific programming language, such as Objective C for iOS and Java for Android operating systems. Native mobile apps provide fast performance and a high degree of reliability. They also have access to a phone's various devices, such as its camera and address book. In addition, users can use some apps without an Internet connection. However, this type of app is expensive to develop because it is tied to one type of operating system, forcing the company that creates the app to make duplicate versions that work on other platforms.
Native app is installed on the mobile device so it can be launched faster than a mobile website or webapp which needs you to know and enter its address on the mobile browser.
(source : http://www.techopedia.com/definition/27568/native-mobile-app)