고개를 끄덕여요 · 고개를 끄덕였어요 · 고개를 끄덕이며 (while nodding)
to nod (one's head); to agree, to show approval
Example
선생님의 설명을 듣고 학생들이 고개를 끄덕였어요.
After hearing the teacher's explanation, the students nodded.
Word parts
고개 = the head; 끄덕 imitates the up-and-down nodding motion.