Treat this as an opportunity to show you know who Weber is and a bit of what he had to say about authority, legitimate domination, and bureaucracy.
To zero in on the last part of the question, you have to get a sense of what we mean by formalistic - it's about following rules, treating things by the rules. The opposite would be informality. And what he means by "impersonality" - remember that while it is nice if the bank manager or teller knows your name, you really don't want them to be treating customers or customers' money in some sort of "personal" manner (better treatment for my friends, etc.). You want the bureaucracy to treat you "like a number." Be sure you can explain this to the proverbial taxi driver.
Who is Weber? What is this from?
Why bureaucratic domination? How does this fit in with "types of legitimate domination"?
Do you make the connection with legal rational?
Can you explain the idea of formalistic here?
Can you explain the idea of impersonality here?
In what sense is ideal typical bureaucracy "formalistic impersonality" taken to the extreme? Why might this be a formidable form of power and domination?
If the world worked in terms of "just following orders"…