This is the 5075th most frequent Russian word.
мобильное
"Mobile" or "portable."
In this instance, 'мобильное' modifies 'мир,' suggesting a world characterized by mobility and the prevalence of mobile technology.
Мы живем в мобильном мире, где технологии развиваются быстро.
We live in a mobile world where technology advances quickly.
In this sentence, 'мобильное' is an adjective modifying 'приложение,' indicating that the application is designed for mobile devices.
У меня есть мобильное приложение для учёбы.
I have a mobile application for studying.
Here, 'мобильное' is an adjective describing 'обучение,' referring to learning that takes place via mobile platforms or devices.