to be confused; to be bewildered; to be taken aback
突然の提案に面食らった。
I was taken aback by the sudden proposal.
初めてのスピーチで面食らっていた。
He looked flustered during his first speech.
突然の質問にも全く面食らわないのが彼女の強みだ。
Never being thrown off by unexpected questions is her strength.