Translation:Let us discuss why you are here.
The indicative and imperative forms of the verb are identical for the first person plural. The imperative mood is due to the word order in this sentence. The indicative word order would be ‘Wir diskutieren…’.
But the English translation is inaccurate because ignores the emphatic word ‘doch’ in the German original, which could be translated as “Do let's discuss why you're here.”
In German verbs, the imperative is only a distinct form for the familiar second-person singular, ‘du’. Otherwise, the imperative, like the interrogative, is indicated by inverting order of the subject and verb. For the familiar second-person singular (‘du’) and plural (‘ihr’), the subject is usually omitted, being obvious from the verb. But for the first-person plural (‘wir’) and formal second-person (‘Sie’), which share the same verb form, the subject is obligatory.