No, jakkesæt has the same singular and plural form. The only way to know which one it is is to look at the sentence. If there is no article, then it most likely plural.
You wouldn't say that in english, you would say a suit or the suit if it were singular.
Yet, my first experience with it was a sentence with no articles, but it was singular and someone said that articles are not necessary with clothes. The subject was singular and that is what tipped us off to it being singular.
The wonders of Danish pronounciation. It's sometimes almost as bad as English. :D