This category has different functions. You will understand if you list. There are various functions related to Android, iPad, iPhone, Apple, etc. These are basically apps for creating apps.
Now if you know how to build apps, you can do that. Otherwise you have to learn from a good training center. But there are rarely any training centers available to teach well in Bangladesh.
So, before choosing a training center, one has to evaluate the quality. How have they taught past trainees, how they are currently working and so on.