This is the 3394th most frequent Arabic word.
كثر
"Kathura" (كثر) means "to be abundant" or "to increase."
The verb 'كثر' here means 'to increase in quantity', and it is used to describe that the streets became crowded due to a higher number of people.
كثر النّاس في الطّرقات اليوم.
The number of people in the streets increased today.
The word 'كثروا' is used as a verb form indicating 'they became many', implying an abundance of children participating in the match.
يحب الأطفال المشاركات الاجتماعية حيث كثروا في هذه المباراة.
Children love social gatherings, so they were many in this match.
Here, 'كثر' serves as a verb to express that goodness and prosperity increased in quantity within the village due to positive actions.