When engineer enters management, what is the most likely problem he finds difficult to acquire?

It would probably be related to human interactions, during their study and early experience, most engineers only interact with other engineers or people with technical backgrounds. 

Becoming a manager means interacting with people from other areas of study or lower education, which means the use of easier terminology become a priority.   

The engineers always take care of technical issues not managerial issues because of that they should get trained in managerial skills 

Thanks for invitation,

I do believe that, he has to enhance in general his "soft skills", and specially for "Time Management, communication and presentation" skills.

thanks

The biggest problem is dealing with the human source, many engineers are not good at the human source

Understanding finance is not easy but engineers can acquire the required knowledge of financial terms and concept by investing some time and also recommended to participate in course called finance for non Finance.

Thank you for the invitation. I agree with the experts answers.

Thanks

I support colleagues answers 

Regards 

Technical jargon and slangs will be difficult to understand for others related to his specific field. It will create communication gap and communication gap is a basic problems which brings other problems.

Thank you for invitation. I am agree with colleagues answer, also looking forward to new answer.