A ladder is a piece of equipment used for climbing up something or down from something. It consists of two long pieces of wood, metal, or rope with steps fixed between them.
N-SING
(社会、组织或系统中晋升或降级的)梯级,阶梯
You can use the ladder to refer to something such as a society, organization, or system which has different levels that people can progress up or drop down.