This is the 11262nd most frequent Russian word.
де
The word "де" in Russian is an archaic or dialectal term meaning "where" or "supposedly."
Here, 'де' is used to introduce a relative clause, specifying 'the place where' something happened.
Он говорил что-то про место, де произошел инцидент.
He was talking about the place where the incident occurred.
In this sentence, 'де' is again functioning as a question word for 'where'.
Де я сейчас нахожусь?
Where am I now?
The word 'де' here is used as a question word equivalent to 'where' in English.