This is the 4062nd most frequent Chinese word.
則於
"則於" means "then with regard to" or "as for."
Here, '則於' is used to connect the action of attending gatherings with the resulting understanding of friends' lifestyles, implying a cause-effect relationship.
他喜歡參加聚會，則於他更了解朋友的生活方式。
He enjoys attending gatherings, thus he better understands his friends' lifestyles.
In this context, '則於' conveys the condition of the rule taking effect, indicating timing or circumstances.
這條規則則於版本更新後生效。
This rule becomes effective after version updates.
Here, '則於' specifies the timing of the event, indicating when it occurs.