In Chinese, you can simply use “很多”, “许多”, “好多”, etc to describe a large quantity of people, things, or abstract concepts, e.g. 广场上有好多人；我哥哥每天都有很多事情要去做；他的心里充满了太多的悲伤; etc, however, in this way you can’t feel the vivid effects, and therefore Chinese set phrases come on stage.
“Many” in Chinese Set Phrases
Set phrases in Chinese can express different kinds of “many 多” vividly to make people feel strongly and imaginably the effect of the related descriptions, e.g. 座无虚席 to describe a full audience/many people; 千军万马 to describe many troops; 五彩缤纷 to describe many colours; 人才济济 to describe many talents, 千辛万苦 to describe many hardships; etc.