I will do mobile apps, mobile app development, android app, iphone app development

Kotlin and Java are the two most commonly used programming languages for Android app development. Swift and Objective-C are the two most commonly used programming languages for iOS app development.

Yes, it is possible to develop a mobile app that can be used on both Android and iOS platforms simultaneously. This is known as cross-platform app development.

Native app development involves developing mobile apps for specific platforms (such as Android or iOS) using the platform-specific programming languages and tools. Hybrid app development, on the other hand, involves using a single codebase to develop apps that can be used on multiple platforms.

The time it takes to develop a mobile app depends on several factors, including the complexity of the app, the number of features, and the platform(s) it is being developed for. However, on average, it can take anywhere from several weeks to several months to develop a mobile app.

To publish a mobile app on app stores, you need to create a developer account with the app store, upload your app's binary file, and provide app store-specific information such as app description, screenshots, and pricing. The app store will then review your app before publishing it to the public.