盈余管理之前我一直理解的就是在会计准则和政策允许的范围内，对利润损益进行操纵，但我看得文章里把盈余管理总是说的很复杂，晕了，盈余管理到底是什么？

It's a very interesting topic.
Here is my understanding:
Earning = Revenue - Expense

Revenue management: it is an emotional issue.
Sometimes, management really wants to maximize it. So they could get more bonus at the end of year.
Sometimes they don't, for leaving it for the late usage purpose.

Expense recognition: another tough question.
Sometimes, you really expect it smaller, so boost your net earnings.
Sometimes, you simply want big bath and
leave more space for the coming years.

There are several books talking about your topic.
So, you are right.
It is really complicated.

I believe talking with your professor will be very constructive and efficient.
She will tell you want he/she wants.

Happy holiday to you my friend.

爱莫能助