Usage of the word "mean" as a verb

A friend was explaining that the Japanese word "mimi" means ears.

But he ended up pointing to his ears saying "This means 'mimi'(in Japanese)". But I felt that he was wrong and should have said it the other way round : "'mimi' (in Japanese) means this(pointing to his ears)". He asked me to explain why he was wrong. I wasn't able to.

I tried finding out the answer for the same and saw this particular instance which I think is similar to this case : to have as its sense or signification; signify: The word “freedom” means many things to many people.

But I was still unable to come up with an explanation as to the reason why it is used in this way.So can anybody please explain why he was wrong? If he is not, could you also explain how he is right? I would like to improve my understanding of the word "means" as a verb :)

Consider this definition of "mean":

to represent or express something intended, or to refer to someone or something

The important part with regard to your question is that it involves "representing" something else.

Since the word "ear" is a linguistic tool used to represent a part of the human body, you would say that "ear means a part of the body used for hearing." The opposite is not exactly true. A physical ear is not a "symbol" or "representation" for the word, so you wouldn't say, for instance,

the part of your body used for hearing means ear

So in that respect, you are correct that your friend should probably say "mimi means." There's a difference between

X means Y

and

Y means X

You might say

That red sign means you should stop.

but it would be nonsensical to say any variant of:

That you should stop means there's a red sign

However, the catch is that when discussing language, "means" often does go both ways, since language is by nature a representational tool that uses symbols to express meaning. So

Mesa in Spanish means table in English

is essentially the same as

Table in English means mesa in Spanish

Because words carry representational value, the verb means is often used going both ways. If your friend had said "Ear means mimi," or "mimi means ear," then either would be acceptable. Only because he pointed to a physical ear does it become strange to attribute "meaning" to the object.