godan verb (-su), intransitive verb
begin to speak; begin to explain
Used when someone starts talking or explaining something, often after a pause or hesitation. The verb focuses on the act of beginning to verbalize thoughts.
彼はしばらく黙っていたが、やがて事情を説き出した。
He was silent for a while, but eventually began to explain the circumstances.
先生が教
When the teacher began to explain the textbook content, the classroom fell silent.