to return someone to a good, healthy, or normal life or condition after they have been in prison, been very ill, etc.

The prison service should try to rehabilitate prisoners so that they can lead normal lives when they leave prison. 监狱应该努力改造犯人，使他们在刑满释放后能重新过上正常生活。

Physiotherapy is part of rehabilitating accident victims. 理疗是对事故受伤者进行康复治疗的一部分。

After 20 years in official disgrace, she's been rehabilitated (= given a positive public image again). 在受到官方贬弹20年后，她终于恢复了名誉。

to return something to a good condition

We need to replace or rehabilitate the bridge. 我们需要更换或是修复这座桥梁。