The wizard of Earthsea is one of my all time favorite books. It has many great qualities, but one of the most intriguing ones is the unique consept of magic. In Earthsea the power comes from knowing the true name of things.
In real life we don't (unfortunately) have magic. But words can still have power. If you can name it, you can change it. It's a lot easier to realize your meaning when you have the correct words for it. It's hard to lak about something you don't have words for.
When speaking about things it's easy to misunderstand the message if the meaning of the words used is unclear. They can often have multiple meanings making it harder to understand others. Challenging and complex ideas might even require new words to be used, or at least some old words reused in new contexts.
It's a good idea to establish a clear lexicon so that it is clear what those words mean in certain context. That can minimize the chance of misunderstanding.
Knowing the true names of things gives you the power to affect those things.
No wonder the master namer was one of the most powerful and respected wizards of Earthsea.