The new political party came into being after years of grassroots activism.

came 是动词 come 的过去式，意思是"来、到达"。 into 是介词，表示"进入某种状态或情况"。 being 是名词，意思是"存在、生存"。 came into being 是一个固定短语，字面意思是"进入存在状态"，引申为"形成、诞生"，用来描述某事物的出现或创立过程。