Translation:What did you say?
The q is a bit farther back in the throat than an English k. The tlh doesn't sound like anuthing in English. It seems to be something like a t combined with the Welsh sound ll (you could look up a Welsh word like "llan" on Google Translate or something to hear the pronunciation). I would say you could put your tongue where it goes to make the t sound and then, instead of letting your tongue release from tge top of your mouth, keep tge tip of your tongue on the top of your mouth and release the air at the sides of your tongue. I know that's complicated, but it's a complicated sound for us.
If you follow this link and click on the word, it will pull up an audio player that demonstrates how the word sounds:
The tlh is a difficult sound for English speakers, because we don't have the sound in English. In fact, when most English speakers say words from other languages that have this sound, they usually do a funny two sound approximation (like the name of the Mexican language Nahuatl). The sound is made by starting with the tongue closed against the roof of the mouth, like you are going to say a "t". But then explode the air out the sides of the tongue so you are making a voiceless "l" (it must explode into the "l" the way the "t" explodes, but at the sides of the tongue instead of at the tip of the tongue). Keep the tip of the tongue on the roof of the mouth, or even bite it between your teeth if you have to.
Oh, I didn't know the Icelandic did.
Yes -- Icelandic ll is something like [tl]; see the IPA in the Wikipedia article on the volcano: https://en.wikipedia.org/wiki/Eyjafjallaj%C3%B6kull
Normal sentences without context or time markers could be in any of the simple tenses. So nuq Dajatlh can definitely be interpreted as, "What will you say?" However, nuqjatlh is not a full sentence and has a special meaning. It is an exclamation you can use when you did not hear or understand something that was just said. Thus it can only apply to the current moment or very recent past, and never the future.
The [n] and [u] are pretty similar to the English sounds in (say) "noon".
The [q] is similar to an English [k] but is pronounce further back in the throat.
[d͡ʒ] is like the English "j" in "judge".
[a] is similar to the "ah" in "father, palm".
[t͡ɬ] doesn't exist in English; it's kind of like the [ts] in "bits" but with the [s] sound replaced by a breathy "l" sound -- the air gets stopped by the [t] and then released along the sides of the tongue for the [ɬ] part. (If you know Welsh, that's the "ll" sound.)
I was right
Nobody can see what you wrote, so if you have questions about why something was not accepted, please always quote your entire answer.
Even better would be if you can make a screenshot showing the question, your answer, and the error message -- upload it to a website and then paste the URL/link to the image into a comment.
First close your tongue on the roof of your mouth exactly like when you start to say a "T". When you say a "T" you build up some pressure above your tongue and then explode that pressure out of the tip of your tongue, but for the Klingon tlh you instead keep the tip of your tongue on the roof of your mouth and explode the sound out of the sides of your tongue into your cheeks.
At the end of the sound, your tongue should be in the position you use to make an "L" with the tip of your tongue on the roof of your mouth behind your teeth and the sides of your tongue dropped to allow air flow.
This transition from the start of a "T" to the end of an "L" can be very difficult since your tongue has never done that before. For some people the tip of the tongue refuses to stay on the roof of the mouth behind the teeth. If you find that you are having that problem, I have a trick you can use to train your tongue.
If you lightly bite the tip of your tongue to make this sound, it will not be able to move. Be careful that you are making the sound come out the sides of your tongue and not sneaking past the tip (which will sound more like an English "TH"). The sound will still not be quite right so, once your tongue has learned to stay put, you will want to stop this and move the tip of the tongue back up behind the teeth.
The question word nuq is usually translated as "what?" and that's clearly where the nuq- in this exclamation came from, but here it is not being used as the separate question word "what?", but rather, instead, it is part of an unusual single word exclamation: nuqjatlh?
I'm actually not absolutely sure where the word stress should fall in an exclamation. We are told how to do it for verbs and for nouns, but not for exclamations. However, if we apply either the verb stress or the noun stress to this exclamation, we wind up with the same thing, so I'm pretty confident in saying that the stress should fall on the -jatlh syllable (even moreso because that seems to be the way I and many other Klingonists naturally say it).
But to answer your question more broadly, here's an excerpt from the section on stress in TKD:
In a verb, the stressed syllable is usually the verb itself, as opposed to any prefix or suffix. If, however, a suffix ending with ’ is separated from the verb by at least one other suffix, both the verb and the suffix ending in ’ are stressed. In addition, if the meaning of any particular suffix is to be emphasized, the stress may shift to that syllable. Suffixes indicating negation or emphasis (section 4.3) are frequently stressed, as is the interrogative suffix (section 4.2.9).
In a noun, the stressed syllable is usually the syllable right before the first noun suffix, or the final syllable if there is no suffix. If, however, a syllable ending in ’ is present, it is usually stressed instead. If there are two syllables in a row both ending in ’, both are equally stressed.