So, you know how you have your own name, right? And you use it to identify yourself to other people? Well, mobile identity is kind of like that, but for your phone.
When you get a new phone, it has its own identification number called an IMEI. This number is kind of like your phone's name. It's unique to your phone and lets your phone company know that it belongs to you.
But mobile identity is about more than just your phone's ID number. It's also about all of the stuff that you do on your phone. You might use your phone to send texts to your friends, take pictures, play games, and lots of other things. All of these things leave little "tracks" behind that show that they were done by you, on your phone.
So, mobile identity is a way of making sure that all of those "tracks" actually belong to you. That way, if something goes wrong on your phone - like if someone else tries to hack into it or steal your information - your phone company can tell that it isn't really you doing those things.
Overall, mobile identity is all about keeping your phone safe and making sure that the only person who can use it is YOU!