to take action so that you are certain that something happens, is true, etc.

I'll just make sure I've turned the oven off. 我要确认一下是否关掉了烤箱。

Make certain (that) we have enough food for the party. 我们要确保聚会上有足够的饮料。

Make sure you're home by midnight. 你务必得午夜前到家。

Jones made sure of his place on the team with three great goals. 琼斯以3个漂亮的进球确保了他在队里的位置。

I think I locked the door but I'll go back and check just to make sure. 我想我把门锁上了，但还是要回去检查确认一下。

See also: make verb (CAUSE TO BE)