This is the 826th most frequent Indonesian word.
tajam
Sharp.
Here 'tajam' is used as an adjective to describe the literal physical sharpness of the knife.
Pisau itu sangat tajam sehingga memotong kertas dengan mudah.
The knife is so sharp that it easily cuts paper.
In this sentence, 'tajam' is used metaphorically to indicate someone has an acute or quick understanding of a subject.
Dia memiliki pemahaman tajam terhadap matematika.
He has a sharp understanding of mathematics.
Here 'tajam' metaphorically describes the vividness and detail in the depiction of an event.