Offline mobile learning means that you can learn things on your mobile phone or tablet without needing to be connected to the internet.
Think of it like having a little school in your pocket that you can take with you wherever you go. You can learn about different subjects like math, science, or even how to speak a new language.
When you have internet access, you can download the materials onto your device so that you can use them later even if you don't have internet anymore.
It's kind of like having a book with you, but instead of just one book, you can have lots of books and different kinds of learning materials all in one place.
So even if you can't get online, you can still learn new things and have fun while doing it!