句子主干是：The aspect of promotion is the focus.
that aims to generate publicity(定语从句,做前面的promotion的定语)
meaning free mention or coverage of a particular product在“——”之后,解释前面的名词publicity.
整句翻译：
The aspect of promotion that aims to generate publicity--meaning free mention or coverage of a particular product is the focus of this chapter
以宣传为目的的促销是本章的重点,这种宣传的意思是免费提及或覆盖特定的产品.
翻译完毕,你看可以不,可以的话,请选为满意答案.希望对你有所帮助,请指出