This is the 18023rd most frequent Russian word.
фишку
"Фишку" means "game token" or "piece" and can also refer to a "gimmick" or "key point" in slang.
In this sentence, 'фишка' refers to a key idea or concept, showing understanding of the main point.
Он сразу понял фишку нашего плана.
He immediately understood the key idea of our plan.
Here, 'фишка' refers to a feature, suggesting something special or unique.
Эта новая фишка на телефоне очень удобна.
This new feature on the phone is very convenient.
In this case, 'фишка' means the catch or main point, emphasizing the essence or trick of a situation.