Here is another discussion:
Te entiendo, pero no te comprendo.
Entender is to understand, as in, I know what you said and I know what the words mean.
Comprender is comprehensive understanding, as in: I can put myself into your shoes and I know why you are saying that
Van a= they are going to, so the subject is 'they'. Te= 'you' is a direct object familiar 2nd person singular, so you can't use 'You' as the subject like you suggested in your sentence.
'No' makes the sentence negative, so it translated 'they are not going to understand you.
For your sentence to work, it would have to be 'no vas a comprender'.
I cannot tell you why, but how.
Let's start with the subject, "they" - "ellos/ellas". The subject influences the conjugation of the first verb, so, since you want to translate "going to", it must be a form of ir - to go. The ellos form of that is van.
Okay, let's put it here.
Next up, the rest of the verb. it's "going to understand". Since you already have a conjugated verb, you have to use the infinitive of the second verb: comprender. The "going to"-future tense is constructed as "ir + a + infinitive". So let's just do this:
Van a comprender.
Then the object. It's a direct object, because you're directly influenced by their non-understanding. See how in English you say "understand you" and not "understand to you" or something. Direct objects don't take a preposition.
Now, since the object is a pronoun, Spanish has this special rule that object pronouns are either to be placed in front of the conjugated verb, or at the end of the infinitive. We can do both because the character limit for a comment is really high. The object form of tú (you) is te (you).
Te van a comprender.
Van a comprenderte.
Last item is the negation. "Not" is an adverb, and adverbs in Spanish have to go before the thing they influence - in most cases that's the conjugated verb, since we're directly affecting the action, making the understanding not happen. Now, in one of our sentences there's already the object pronoun in front of the verb, so the no goes before that.
No te van a comprender.
No van a comprenderte.
And so we're done.
Many people seem to be confusing the subject with the direct object in this sentence. Remember, the direct object goes DIRECTLY before the first conjugated verb in the sentence. The first conjugated verb is "ir" and the subject is implied within the conjugation, "they".
I suppose if you wanted to clarify the context of the sentence more, you could say "No ellos te van a comprender." That sentence means the same thing, but does not omit the subject pronoun from the sentence.
Duolingo, why am I suddenly having to scroll from the very beginning of the Spanish lessons to get to the question topic that I'm working on after every set of (5) questions?! This has been happening for the last couple of days, and it's pretty annoying. Some kind of update seems to have happened since there were multiple crashes of the app a few days ago and perhaps it was not q.a.'d sufficiently.