This is the 8th most frequent Turkish word.
en
The Turkish word "en" means "most" or "the most" and is used to form superlatives.
In this sentence, 'en' is used to express the superlative form of 'çalışkan' (hardworking).
O, bu sınıftaki en çalışkan öğrenci.
He is the most hardworking student in this class.
Here, 'en' intensifies 'iyi' (good) to indicate the utmost level.
Bu konuyu en iyi şekilde anlamamız gerekiyor.
We need to understand this topic in the best way.
In this usage, 'en' acts as an adverb meaning 'finally' or 'in the end.'