Some weeks ago, she was hired by a famous advertising company, widely known for its ironic ads.

advertising 是动词 advertise 的现在分词形式作形容词用。advertise 由前缀 ad-（表示"朝向"）和词根 vert（来自拉丁语 vertere，意为"转向"）组成，字面意思是"使转向某事物"，引申为"宣传、做广告"。 advertising company 指专门从事广告业务的公司，即"广告公司"。