It's referring to an analogy or parable. Say you had an item that was solid - a book, or an apple, or a baseball. If you didn't want to lose it, you would hold onto to it tight. Some other possessions don't work that way. If you have a handful of sand or water, you need to cup your hands loosely in order to keep it. If you squeeze them into fists, you'll actually lose possession of your valuable sand or water. If conditions become threatening to your possession (it gets windy, say) you can't just hold on tighter. Even though that works for some things, it doesn't work for sand or water.
Some people apply this analogy to money. When companies squeeze on to their money tighter by cutting back budgets, demanding more paperwork, installing timeclocks to be sure everyone is working enough, and so on, they often lose more money than before they did all that. Once you've established that money in a company acts more like sand or water in your hands than like an apple in your hands, you can just refer back to the analogy without having to give the long explanation of why expenses would go up when you started cutting back budgets, or people would produce less when you demanded they prove they are working more hours, and so on. That explanation is long and perhaps not everyone agrees with it. The image of sand or water dribbling out of your grasp while you desperately try to hold it, that will get you nods of agreement and typically also an emotional response.