It means to act or take advantage of an opportunity at the right moment, when the person is most likely to succeed.

eg: You should strike while the iron is hot.

     If you want to get a higher degree, you should strike while the iron is hot.

Note:

    Strike while the iron is hot的意思为趁热打铁，就是机会一旦来临，一定要抓住，才能得到最好的结果。

    例如：你要打铁趁热。

    假如你想取得高学位，就应该趁热打铁。