The words and phrases used to describe martial arts are an important aspect of mental training. In many organizations it is a requirement that students study such terms in their own language as well as the original language of the martial art.
Firstly, what is the purpose of doing this? It is easy to see because different movements have specific names: it speeds up the communication of which movement you must do. There can also be slight variations in body position, section, power, transition to and purpose of different techniques, and a refined system of terminology that allows us to identify this.
Secondly, and a probably more important question, what is the purpose of learning martial arts terminology in another language? There are several reasons.
It is excellent for standardizing movement names across separate organizations. Often, organizations will use different terminology to describe the same moves. This is inconvenient when joint or open competitions are held, and so using the original language can help to clarify what is meant.
If the martial art you are studying comes from another country, it could be seen as ignorant and arrogant to want to learn all of the movements and skills, but nothing about the culture of that country. Learning just a small part of their language is one way to gather some information on their culture.
From the point of view of examinations, organizations to not want to be promoting thugs to their senior ranks. By requiring that students learn something academic like terminology, it acts as a barrier against such people.
Also within gradations, sometimes a person is incapable of performing the movements, or maintaining the physical effort, for example, the elderly. Yet if this person is enthusiastic and motivated, they should be granted recognition within the martial art if they show themselves to be knowledgeable about it. The theoretic aspects can be an alternative means to grade a pupil, and a way to show examiners a pupil's attitude.
And despite most importantly, martial artists should be knowledgeable on all topics within their martial art, otherwise how could they ever be considered an expert? This is more important for higher grades, particularly those trying to achieve black belt levels.
Learning the terminology, and indeed the theory in general, is something that many people find difficult. Unfortunately there is no substitute for hard work in this discipline, but there are educational techniques which you can use to make the process more effective and more natural.
You will, at some point, need to sit down and try to match up the words in one language with the words in another. This can be done with the use of flash cards, quizzes, or simply writing a list and covering one side of it. Repetition is everything, keep doing this until you have every word cemented into your memory, and then do this every day until you can recall the whole lot inside-out and back-to-front.
The previous method is unavoidable, now time for the interesting methods. An effective way to associate words with movements is, whenever you perform a movement, say its name in both languages. If you do this every time, you will very quickly become proficient. In fact, this principle should apply to everything in your lessons. If you can say it in both languages, then do, regardless of whether you're teaching, practicing forms, doing line work, whatever.
Another way to make the task seem easy, is to go beyond the requirements for your level. Doing this makes the language appropriate to your level seem ridiculously simple, and you become proficient. You will also impress examiners with your advanced knowledge and effort.
Once you have this knowledge, it will stay there for a long time, but you may occasionally need a refresher course.