Learn Dutch: We hebben de strenge regelgeving gerespecteerd, hetgeen de baas waardeert. - We respected the strict regulation, which the boss appreciates.

hetgeen is a formal relative pronoun that means "which" or "that which". Both hetgeen and wat are grammatically correct to refer back to a whole previous clause (the fact that you respected the rules). However, hetgeen is used in formal, written, or business contexts, whereas wat is what you will hear in everyday speech.

Could I use die instead of hetgeen to mean "which"?

No, and this is a common trap! If you used die here, it would point back to the specific noun de regelgeving, meaning the boss appreciates the strict rules themselves. Because you want to refer back to the entire action of the previous sentence (the fact that you respected those rules), you must use wat or the formal hetgeen.

Why does the verb waardeert go at the very end of the sentence?

hetgeen introduces a relative clause, which functions as a subordinate clause. In Dutch subordinate clauses, the conjugated verb is pushed to the end. Therefore, the normal order of de baas waardeert changes into hetgeen de baas waardeert.

Why does streng get an -e ending to become strenge?