一阵 (yī zhèn) is a classifier for sudden, short-lived events: 一阵风 (a gust of wind), 一阵雨 (a spell of rain), 一阵笑声 (a burst of laughter), 一阵疼痛 (a wave of pain).
history
The original meaning of 阵 is a military formation (阵法). This still appears in words like 阵地 (zhèndì, position/front) and 阵容 (zhènróng, lineup).