I have a query about the mind boggles? It's too hard to understand for English learner. so what does mean the mind boggles?
To boggle, like many English verbs, can be both transitive or intransitive.
The complexity of this system boggles the mind.
The mind boggles at the complexity of this system.
In face of such complexity, the mind boggles.
"Mind-boggling" or to "boggle your mind" is an expression that means overwhelming, startling, amazing, or astonishing.
Here is a definition:
having a very powerful or overwhelming effect on the mind
a mind-boggling [=stunning] performance
amazingly or confusingly large, great, etc.
a mind-boggling array of options
He received a mind-boggling $200 million in pay.
The sheer vastness of space is mind-boggling.