北米では、肩をすくめることは「知りません」を意味する。

、「」。

In North America, shrugging your shoulders means 'I don't know.'

Literal

North-America [in-では], shoulders [object-を] shrug thing [topic-は] 'don't-know' [object-を] mean.

北米 ('North America') is a compact compound. 肩をすくめる ('to shrug one's shoulders') is a set expression. 知りません as a quoted phrase (in 「」) represents the meaning conveyed. 意味する ('to mean') is a noun+する verb taking the meaning as を. A cultural observation comparing non-verbal communication.