This is the 2107th most frequent Arabic word.
جيد
Good.
Here, "جيد" acts as an adjective to describe "الكتاب", specifying its quality.
الكتاب جيد جدًا.
The book is very good.
In this sentence, "جيد" is part of the phrase "حالة جيدة", describing the state or condition.
هل أنت في حالة جيدة؟
Are you in a good condition?
Presenting "جيد" as an adjective describing "عمل", evaluating the quality of the action performed by the student.