Used to say that everyone's help is needed in a certain situation, usually a difficult one

The building was on fire, and the firefighters needed all hands on deck to evacuate everyone

L'edificio era in fiamme e i vigili del fuoco hanno avuto bisogno di tutto l'aiuto possibile per evacuare tutte le persone

This is an emergency situation and we are going to need all hands on deck to get out of it safely

Siamo in una situazione di emergenza e abbiamo bisogno dell'aiuto di tutti per uscirne sani e salvi

The project assigned to the students was not a simple one, so it became an all-hands-on-deck task

Il progetto assegnato agli studenti non era per niente  semplice, per cui è stato necessario aiuto, collaborazione e lavoro da parte di tutti

This expression originates from nautical tradition. In origin, it was used to literally call all members of the ship's crew to the main deck, so that all of them could work together trying to solve an emergency situation