Learn French: Le détective écrit un rapport. - The detective is writing a report.

In French, the present tense (écrit) translates to both "writes" and "is writing." French doesn't have a separate tense for actions happening right this second. If you really need to emphasize that the detective is busy writing at this exact moment, you could use the phrase être en train de (to be in the middle of): Le détective est en train d'écrire un rapport.

Is écrit an irregular verb?

Yes, it is the singular "he/she/it" form of the irregular verb écrire (to write). As an A2 learner, you will see this verb a lot. Its present tense pattern is: j'écris, tu écris, il/elle/on écrit, nous écrivons, vous écrivez, and ils/elles écrivent.

The word rapport looks exactly like the English word "rapport." Do they mean the same thing?

They are partly "false friends." In English, a "rapport" usually means a friendly, empathetic connection with someone. In French, un rapport most commonly means a physical or official "report," like a police report or a business document.

Since we are practicing negative pronouns, how would I use this vocabulary to say "The detective wrote nothing"?