Why is there no article?
Occupations, jobs, professions do not need an article in French.
Could you please clarify these two sentences: c'est un juge; ce sont des soldats. Does this mean the article "des" in the second sentence can be omitted. Thanks a lot.
"des" is the plural indefinite article for "un" or "une" and it cannot be omitted in such a sentence:
As "juge" is a profession, you can also say the same thing with a real pronoun and no article:
Thank you! So it means that we normally don't to use articles with être+ a profession but the articles are needed when we use c'est or ce sont + a profession?
Yes, and note that you don't use articles with "devenir + a profession" either.
Why not "He is an assistant."? Who on Earth would write administrative assistant?
There are lots of kinds of assistants that don't to secretarial-type labor. The kind that do are sometimes called "administrative assistants." In short, it doesn't back-translate. What would back translate is adjoint, assitant, or aide.
Am I right to assume the word for this profession is, unlike other professions in French, never declined according to gender (and is always written as if the job holder was female?)
You are right, there is no change according on gender, simply because of the -aire ending, which is bi-gender: un/e commissaire, un/une fonctionnaire...
what is a secretary?
Originally someone who kept the secrets of someone important, nowadays it's another word for administrative assistant (though lets face it they usually know most of the bosses' secrets)
why not "c'est secretaire"?
Back translation: this is secretary.
There is no "un" in the text
The reason is that we translate correct and natural French (il est secrétaire -or- C'est un secrétaire) to correct and natural English: he is a secretary.
Because that is the way we say most professions, and they might not be the only one.