defense
In Italian, 'difesa' is the word used for 'defense'. It is used in a similar way to English, in contexts such as sports, military, and legal situations. For example, in soccer, a team's 'difesa' is its defense line, and in law, a 'difesa' is a defense argument.
Our main task is the defense of the nation.
This sentence is stating that the primary duty or responsibility (our main task) revolves around protecting or guarding the country (defense of the nation).
You must learn the art of defense to play chess.
In this context, it suggests that in order to play the game of chess, it is necessary to understand or be skilled in defensive strategies (the art of defense).
The client's defense will be difficult.
This phrase suggests that representing or advocating for the client in a legal context (the client's defense) is going to be challenging or problematic.