This is the 716th most frequent Turkish word.
bilgisi
Knowledge or information.
The word 'bilgisi' here refers to the possession and proficiency in a specific subject, mathematics.
Ali'nin matematik bilgisi çok iyi.
Ali's knowledge of mathematics is very good.
In this sentence, 'bilgisi' highlights the lack of awareness or information regarding a specific matter.
Bu konuda hiçbir bilgisi yok.
He/She has no knowledge about this subject.
The term 'bilgisi' is used to refer to expertise or extensive understanding in a field, which in this context is history.