It is the responsibility of the parents not to fight or use any foul language in front of the kids, as they may learn and use it in front of others.

foul 的意思是"肮脏的、下流的"，在这里引申为"粗俗的、不雅的"。 language 的意思是"语言"，指人们交流时使用的词语和表达方式。 foul language 指"脏话、粗话"，即那些被认为不礼貌、冒犯或下流的词语表达。