What is the use of a Manager class?

I can't understand what is the use of the so called Manager classes(Game manager/security manager/round manager in a game ..etc)

some say that it basically manages interactions between multiple objects others say it is a bad practice and should be avoided

let's say i have a game with multiple rounds what would be the use of the (round manager / game manager / player manager etc..) in this case?

and if it is considered to be a symbol of bad design then what would be the perfect design if you want to make multiple different classes interact with each other?