"Elle travaille dans l'industrie du divertissement."
Translation:She works in the entertainment industry.
Well, that's a tough one.
I think divertissement has two slightly different meanings here.
A film de divertissement is more or less a genre. Like a horror movie or a love story. Here divertissement, from se divertir (having fun) is enjoyable, funny and not too serious (light-minded?)
In L'industrie du divertissement, Le divertissement is the entertainment as whole industrial and economic sector, with its companies, shows and artists.
Keep checking the discussion pages in this module. Sitesurf gives a couple long explanations, but I don't know how to link to them. (Sorry!)
For me as an intermediate student, the most useful "rule" or principle is collocation. This simply means that in fluent speech, certain words tend to occur together. For example, the three words "industrie du divertissement " often occur together when French people speak (or write). As a student, I can easily learn these three words as a chunk. Then I can use that chunk in an intelligent French conversation. I have no idea about a rule why these particular words occur together in a certain order. But I do know what they mean, and I can use them together intelligently.
I think that's an underlying logic for learning a second language. Learn what they say and how they say it, with less concern for why they say it that way. This has been a helpful guideline for me, and I hope it helps others also.