In the Humean Theory, as stated before, Laws of Nature are statements of the uniformities (regularities) in the world. For example, laws of nature are mere descriptions of the way the world works. In this view, we are told that if it were logical that there's a causal relation from A's to B's then it would be known a priori. Hume insists that for any cause it's logically possible that its usual effect will not follow from it. Ultimately, it comes down to empirical experience; causal relations are observed and instantiated based on experience.
In a more narrow sense, the laws of nature are nothing more than true universal generalisations. For example, x is true because we have always observed that x happens. An example cited in the text: if it is a law that copper conducts electricity, then what makes it a law, is the fact that all pieces of copper (universally, across time and space) conduct electricity.