This is the 5th most frequent Bulgarian word.
че
"Че" means "that" (used as a conjunction).
In this example, "че" is used as an interjectory particle, adding emphasis or a questioning tone to the phrase.
Че какво става тук?
What is happening here?
Here, "че" is used to emphasize or assert the clause it introduces, marking the importance or reality of the statement.
Виж, че е важно да слушаш.
See that it's important to listen.
In this sentence, "че" is used as a conjunction to introduce a subordinate clause that provides the content of the statement.