If you don't know what a service bus is good for, then you don't need to know Mule ESB. A Service Bus can be a wise integration strategy for loosely coupled information systems:
What is Mule ESB? | MuleSoft
Well, as the title states we'll be addressing software development topics (mainly in English). Topics will be quick and short and most probably aligned with the training "problems", sorry, programs I am involved in. PS. Some links are "internal" (not publicly available): If you are not able to reach it, google will find you a publicly available information source for sure. Happy trails to you.