This is the 5694th most frequent Russian word.
признаком
"Признаком" means "a sign" or "an indication."
In this sentence, 'признаком' is used to indicate a characteristic or a distinguishing quality of someone who is educated.
Знание иностранных языков является признаком образованности.
Knowledge of foreign languages is a sign of being educated.
Here, 'признаком' expresses a feature or an indicator that points towards courage.
Отсутствие страха перед трудностями — это признаком мужества.
The absence of fear of difficulties is a sign of courage.
In this context, 'признаком' denotes a clear and evident trait.