Questions & Answers about Det er legen som roper navnet hennes.
What does the construction Det er … som do here?
It’s a cleft sentence that puts focus on the element after det er. Here it highlights that it’s specifically legen (the doctor) who is doing the action. A neutral, non-cleft version would be: Legen roper navnet hennes. The cleft is common when answering or correcting: Hvem er det som roper? – Det er legen som roper.
Why is som used, and can I omit it?
Som is the relative word (who/that) introducing the clause and functions as the subject of that clause. When som is the subject, you must include it: Det er legen som roper … If som were the object, it could often be omitted: Det er legen (som) hun hilser på. But not in your sentence.
Why is the verb in simple present (roper) when English says “is calling”?
Norwegian simple present covers both habitual and ongoing actions. So roper can mean “calls” or “is calling” depending on context. You normally don’t need a special progressive form.