This is the 69th most frequent Azerbaijani word.
etdiyi
"Etc [...] " in English means "done by him/her/it" or "that he/she/it did."
Here, 'etdiyini' is used to describe the action of 'doing something' in the past, reported speech.
O, səhər yeməyində çox maraqlı bir şey etdiyini dedi.
He said he did something very interesting at breakfast.
In this sentence, 'etdiyi' functions as a connector in a relative clause describing an action attributed to the teacher.
Müəllimin tələbələrin inkişafını təsdiq etdiyi məlum oldu.
It became clear that the teacher confirmed the students' progress.
Here, 'etdiyi' modifies the noun 'act' to specify that it was performed by his friend.