Hybrid mobile applications are like any other applications you will see on your mobile. They get easily installed on your mobile device. You can look for these apps in the App stores. By using these apps, you can engage your friends via social media, play games, track your health, take photos and much more.
Hybrid mobile applications are developed using a combination of web technologies like CSS, HTML, and JS as same as websites on the internet. The major difference is that hybrid applications are hosted inside a native app which further uses a mobile platform's WebView. Here, WebView is a chromeless browser window which is typically configured to run fullscreen.
Unless you are the one who really cares about this, it is not terribly important. What all matters are how your hybrid mobile application development is going to work in the long run as no one will care about how it was built. A hybrid mobile application is said to be good if it performs well for its users.