i have a question
 

languages like japanese and english in history absorb a lot of foreign words，if a person is uneducated or not well-educated，can this person know what a foreign word means in his or her mother tongue，or distinguish its etymology
such as freedom-liberty

If a person is uneducated then of course the answer is "no".

Etymology is a highly specialised field of study. Regardless of the degree of formal education, most people will know the origins of particular words only if there has been, at some time, a compelling reason to investigate the origins of that word. Sometimes though, it will have been merely a matter of idle curiosity.
Borrowed words do not necessarily retain the same range of meanings as applied in the original language - For example: In September 2008, the governor of Hyogo used "chance" with one of the English language connotations that are not included in the Japanese language use of チャンス. 「相当ダメージ受けますからこれはチャンスですね」. It caused a furore.

YouTube - 井戸敏三「なぜ自衛隊の派遣が遅れたら２０００人犠牲 者が増えたのか、

I think with a high school education the average American can tell you that "catphobia" sounds a bit funny. While they may not know what "ailurophobia" means, they will recognize it as sounding more like a "correct Greek-derived English word."

amazingly, even though they use katakana to spell the word, some people think certain foreign words are actually japanese.

mind you, with the way they pronounce some foreign words, it might as well be japanese:p

All foreign words are made to fit Japanese pronunciation. And you are right, they might as well be Japanese, as they are adopted into the language.

Man, MMM, where were you when a couple people were trying to convince me in the Japanese board that a loanword is not part of the language that borrows it?

Like, there were people telling me that "arachnophobia" isn't an English word because it comes from Greek, and "sushi" isn't an English word because it comes from Japanese.

I was trying to tell them that if a word is used in a language regularly, it's a word in that language. This caveat about "regularly" is meant to exclude stuff like considering "omnia praesumuntur contra spoliatorem" as English because it's used very occasionally in some US court opinions.

true, and its the same with any language, but japanese makes a clear distinction between foreign and local words via a seperate alphabet, so one would expect they would know that a word was foreign regardless of whether they know where it comes from or not.

You would think, but you'd be wrong in a few instances. The fact that Japanese has お茶 instead of ご茶 shows that they've forgotten that 茶 comes from Chinese.

Then you have a language called Piraha, which is so different that importing foreign (loaned) concepts is always a huge hassle, thus impossible.

Pirahã language - Wikipedia, the free encyclopedia

1. no numbers
2. very simplified kinship term(s)
3. no abstract color terms

This is the best and the rarest example how language completely constrains a culture, lifestyle, and make it impossible to understand loanwords.