"说含沙射影的话" can be translated into English as "make insinuating remarks" or "speak in an indirect and derogatory way".
Here are some example sentences to illustrate the usage:
1、 He often makes insinuating remarks about his colleagues behind their backs.
(他经常在背后对同事说含沙射影的话。)
2、 It's not polite to speak in such an indirect and derogatory way about others.
(这样含沙射影地谈论别人是不礼貌的。)