to change something such as a plan, opinion, law, or way of behaviour slightly, usually to improve it or make it more acceptable

Instead of simply punishing them, the system encourages offenders to modify their behaviour. 这个制度并不是单单惩罚犯罪者，而是鼓励他们改正自己的行为。

The proposals were unpopular and were only accepted in a modified form. 这些建议不受欢迎，修改之后才得以接受。

If a word or phrase modifies another word or phrase used with it, it limits or adds to its meaning.

In the sentence "She ran quickly" the adverb "quickly" modifies the verb "ran". 在句子 She ran quickly 中，副词 quickly 修饰动词 ran。