A man must do what has to be done, no matter if it's difficult or dangerous. Sometimes it is used ironically

Dear Michael, I know the situation is difficult, but you are a man and have a family to take care of. There are things you can't walk away from: a man's got to do what a man's got to do!

Caro Michele, so che è una situazione difficile, ma sei un uomo e hai una famiglia da proteggere. Ci sono cose a cui non puoi sfuggire. Devi fare quello che è giusto!

"Do you really have to shovel the snow from your driveway when you know that tomorrow we are going to get more snow?" "You gotta do what you gotta do!"

"Devi proprio spalare la neve dall'ingresso anche se sai che domani nevicherà ancora?" "Si fa quel che si deve!"

"Ten beers? Are you sure?" "He offered me ten large beers. A man's gotta do what a man gotta do: cheers!"

"Dieci birre? Sei sicuro?" "Beh, mi ha offerto dieci birre grandi e non ho scelta, perciò: salute!"

Phrase originated in the USA. Although actors John Wayne, Alan Ladd and Charles Heston have been credited with saying a similar phrase in one of their movies, it looks like that the closest first citation appeared in J. Steinbeck's novel The Grapes of Wrath (1939 - chapter 18): "I know this man - a man got to do what he got to do"