This is the 42nd most frequent Armenian word.
երբ
"երբ" means "when" in English.
In this question, 'երբ' functions as an interrogative adverb asking about time.
Երբ ենք մենք գնալու արձակուրդի։
When are we going on vacation?
The word 'երբ' is used as a temporal conjunction to introduce a subordinate clause specifying a time.
Երբ դու կգաս, մենք ընթրիք կսպասենք։
When you arrive, we will wait for dinner.
Here, 'երբ' is used as a relative conjunction referring to a time in the past.