to have something well organized or under control

The police have the situation in hand. 警方已经控制了局面。

How come there's a problem? I thought you had everything in hand . 怎么会出问题？我以为你全都安排好了。

If you have something in hand, you have not yet used it and it is still available.

I had enough money in hand to buy a new car. 我手头有足够的钱买一辆新轿车。