"I am listening because you are speaking."
Translation:Ich höre zu, weil Sie sprechen.
zuhören (= listen) is a verb with a separable prefix.
While English uses the preposition to in order to designate who / what one is listening to, German uses the dative case for that.
Ich höre dir zu. / Laß uns ihr zuhören.
= I'm listening to you. / Let's listen to her.
In this case it happens not to make a difference. This is because the clause “Sie sprechen” only has two elements to begin with, so the verb appearing in second position (as required by denn in this case) or at the very end (as required by weil) both produce the same result. But for longer sentences there will be a difference.
The verb is in second place there: Sie sprechen. (denn just links the clauses and doesn’t occupy a space for itself.) It just so happens that the clause also ends after the second position, so the second position is the same as the last one. But if we add an object: Ich höre zu, denn sie sprechen mit mir. Compare Ich höre zu, weil sie mit mir sprechen.
That said, weil in particular is currently in transition to becoming a coordinating conjunction – i.e. people are more and more often using it exactly the same way as denn, with the verb in second place. However that is not generally accepted yet and will still be counted as a mistake in a test, so I suggest you don’t use that order yourself. Just don’t be surprised if you hear things like weil sie sprechen mit mir from native speakers.
For those who, like me, were surprised (maybe even ambushed?) by the concept of separable verbs, I found a pretty clear discussion of them here: https://www.fluentu.com/blog/german/german-separable-verbs/
No, zuhören is a trennbares Verb (separable verb). It separates after the zu (zu|hören). In simple tenses, like the present tense, the prefix is sent to the end. So it can only be "ich höre zu".
Compound tenses and infinitives cause it to come together, but possibly with another piece between the prefix and main part of the verb:
Modal verb example: ich will zuhören (modal verb + normal infinitive)
Future example: ich werde zuhören (werden + normal infinitive)
Present perfect (Perfekt) example: ich habe zugehört (auxiliary verb + past participle, which adds the -ge- in between)
Zu-infinitive example: ich habe das Radio angemacht, um zuzuhören. (without a modal verb, -zu- gets added in between to form the zu-infinitive)
Somehow the format of the explanation was messed up for me and I saw some of the raw HTML. This is what I saw: "Unlike English, German has no "-ing" form. So "Ich esse" means "I eat" < strong > and < / strong > "I am eating"." I put this here because the "report" feature didn't have a section for this type of information.