The words themselves don't contain the power, the words are portals or conduits, like wires that connect up currents and circuits. For example, right now I am speaking to you, you are reading these words, but the words themselves are just triggering both of us. What's important is what they do, inside of me as I speak them, and to you as you read them. As I write them and as you are reading them, changes are occurring in my brain and in your brain which will lead to both of us having specific thoughts and actions, some of which you and I are not even in control over. The mere act of writing or reading these words evokes certain energies within us that are already present and subtle. It is like chemistry, the speaking of certain words in a certain way just activates "events" which occur due to the combination of what Agrippa and others would call "occult virtues" - forces that are unknown to us, or perhaps incomprehensible to us, but nevertheless are responsible for the "why" certain words cause certain things to happen when you speak them or someone reads them.
The principle is the same as ordinary language, you speak the words and names that "resonate" with whoever or whatever you are trying to communicate with, and it causes things to happen, or it doesn't. If I speak French to you, and you only speak English, and in French I ask you what time it is, you won't know how to answer me unless I ask in English. It's really that simple.